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MANUAL  OF  PHOTOGRAPHY. 


A 


MANUAL 


HOLOGRAPHY 


INTENDED  AS  A 


TEXT  BOOK  FOB  BEGINNERS  AND  A  BOOK  OF  REFERENCE 
FOR  ADVANCED  PHOTOGRAPHERS. 


BY 

M.  CAREY  LEA. 

SECOND  EDITION, 

REVISED  AND  ENLARGED. 


PHILADELPHIA: 
PRINTED  FOR  THE  AUTHOR. 
1871. 

/ 


Entered  according  to  Act  of  Congress,  in  the  year  1871,  by 
M.  CAREY  LEA, 

in  the  Office  of  the  Librarian  of  Congress,  at  Washington.  All  rights  reserved. 


PHILADELPHIA : 

COLLINS,  PP.INTER,  705  JAYNE  STREET. 


PREFACE  TO  THE  SECOND  EDITION. 


In  preparing  a  second  edition  of  this  manual,  rendered  necessary 
by  the  early  exhaustion  of  the  first,  the  author  has  endeavored  as 
far  as  possible  to  include  all  the  information  useful  to  the  working 
Photographer.  A  very  considerable  portion  of  the  matter  in  the 
first  edition  has  been  cancelled  and  rewritten,  and  over  a  hundred 
pages  have  been  added,  so  that  fully  one-half  of  the  book  is  new. 
The  number  of  engravings  has  been  also  nearly  doubled :  all 
have  been  engraved  expressly  for  this  manual,  and,  with  two  or 
three  exceptions  only,  all  have  been  made  from  original  drawings 
of  the  author. 

The  present  edition  also  contains  the  results  of  several  trains 
of  investigation  by  the  author,  hitherto  unpublished.  Some  of 
them  he  hopes  will  be  found  of  material  practical  importance, 
especially  those  relative  to  “permanent”  printing-paper  and  to 
water-proof  negative  varnishes.  The  arrangement  adopted  in  the 
first  edition  has  been  continued  in  this.  The  first  part  gives  a 
short  and  clear  course  of  instruction  for  beginners.  In  the 
subsequent  parts  the  various  subjects  are  treated  of  in  detail. 


June,  1871. 


CONTENTS 


PART  I. 

INTRODUCTION  TO  PHOTOGRAPHY. 

PAGE 

Chapter  I.  Selection  of  Materials . 9 

II.  Making  the  Negative . 17 

III.  Printing . 44 

IY.  General  Rules  for  Beginners . 47 

PART  II. 

PHOTOGRAPHIC  OPTICS  AND  THEORY  OF  PERSPECTIVE. 

(Tr after  I.  General  Optics . 52 

II.  Of  Lenses . 56 

III.  Faults  incident  to  Spherical  Lenses  .  .  .  .  .  58 

IV.  Focal  Lengths  of  Lenses . 66 

V.  Photographic- Objectives . 78 

VI.  Photographic  Perspective . 97 

PART  III. 

PHOTOGRAPHIC  MANIPULATIONS. 

Chapter  I.  The  Dark  Room . 107 

II.  The  Glass  Room .  .  .  114 

III.  Pyroxyline  and  Collodion . 126 

IV.  The  Negative . 147 

V.  Ambrotypes  and  Ferrotypes  .......  188 

VI.  Portraiture . 190 

VII.  Landscape  and  Architectural  Photography  ....  208 


CONTENTS. 


yiii 

PAGE 

Chap.  YIII.  Composition . 234 

IX.  On  Copying  .  251 

X.  The  Stereoscope . 256 

XI.  Microphotography  and  Microscopic  Photography  .  .  258 

XII.  Development  on  Paper . 260 

XIII.  Silver  Printing  . . 269 

XIY.  Failures  in  Photographic  Operations . 301 

XV.  Out-door  Photography . 344 

XYI.  Dry  Plate  Photography . 351 

XYII.  Dry  Processes . 364 

XYIII.  Negative  Yarnishes . 375 

XIX.  Treatment  of  Residues . 379 

XX.  Photography  on  Glass  and  Enamel,  and  Collodio- Chloride 

Printing,  &c . 383 

XXL  Carbon  Printing  . . 398 


PAET  IV. 


THEORETICAL  CONSIDERATIONS. 

Chapter  I.  General  Observations . 404 

II.  Action  of  Light  on  Silver  Compounds  ....  406 
III.  Action  of  Yarious  Portions  of  the  Spectrum  .  .  .  413 


PART  Y. 

Chapter  I.  Photography  in  its  Relations  to  Health  ....  415 

II.  Chemical  Manipulations . 420 

Addenda  .............  431 


A 


MANUAL  OF  PHOTOGRAPHY. 


PAET  I. 

INTRODUCTION  TO  PHOTOGRAPHY. 

✓ 

CHAPTER  I. 

SELECTION  OF  MATERIALS. 

I  1.— Selection  of  Photographic  Lenses. 

The  information  first  wanted  by  the  beginner  will  be  as  to  his 
materials,  and  especially  as  to  his  lenses.  They  are  to  form  the 
image  which  it  will  be  his  part  to  render  permanent,  and,  unless 
they  are  right,  his  work  will  never  be  satisfactory.  And  they 
must  not  only  be  good  in  themselves,  but  expressly  suited  for 
the  work  which  he  proposes  to  do. 

Such  a  thing  as  a  universal  lens  does  not  exist.  One  combi¬ 
nation  is  best  for  one  purpose,  another  for  another. 

For  Landscapes  the  best  lenses  are  the  View  Lens,  the  Rapid 
Rectilinear,  and  the  Steinheil  Aplanatic.  If  architectural  subjects, 
or  any  others,  are  introduced,  in  which  straight  lines  must  be 
preserved,  the  view  lens  will  be  unsuitable,  because  it  slight^ 
distorts,  and  although  this  distortion  is  of  no  consequence  when 
buildings  are  not  introduced,  it  will  be  a  sufficient  reason,  when 
such  are  included,  for  using  a  lens  of  which  the  stop,  or  dia¬ 
phragm,  is  central ,  that  is,  between  two  lenses,  as  in  the  case  of 
the  second  and  third  of  the  above-mentioned  objectives. 

The  view  lens  has  also  this  fault,  that  it  includes  but  a  small 
angle  of  view,  or,  in  other  words,  but  a  small  portion  of  the 
scene  at  which  it  is  exposed.  This  defect  has  been  remedied  in 
Dallmeyer’s  wide-angle  view  lens,  of  which  the  writer  thinks 
very  favorably  ;  it  is,  however,  not  adapted  for  architectural  sub¬ 
jects,  for  the  reason  already  given. 

2 


1 


10  INTRODUCTION  TO  PHOTOGRAPHY. 

The  lens,  whether  single,  double,  or  triple,  is  termed  an  Objective. 
The  single  lens  has  its  stop  in  front,  that  is,  on  the  object  side, 
and  the  concave  side  of  the  lens  must  always  be  turned  also 
towards  the  object.  Sometimes,  in  cleaning  the  lens,  it  may  hap¬ 
pen  that  it  is  set  back  wrong  side  foremost,  the  effect  of  which,  is 
very  injurious.  In  all  cases  when  any  lens  is  taken  to  pieces  to 
clean,  the  utmost  care  must  be  used  to  replace  everything  exactly 
as  before. 

For  Portraits  there  is  but  one  lens  proper,  and  that  is  the 
“portrait  combination,”  invented  by  Petzval,  and  made  by  many 
excellent  opticians  in  all  parts  of  the  world.  For  groups  the 
Steinheil  aplanatic  is  the  best  lens ;  it  is  often  applied  also  for 
taking  portraits,  which  may  be  obtained  of  large  size  with  com¬ 
paratively  small  lenses,  at  the  expense,  however,  of  rapidity  of 
action.  Triplets  were  formerly  much  used  for  groups,  but  are 
now  superseded  by  the  lens  just  named. 

For  copying  engravings,  plans,  maps,  &c.,  any  lens  with  central 
stops  may  be  used,  except  the  portrait  combination,  which,  as 
well  as  the  view  lens,  is  unsuited  for  such  work.  In  copying,  a 
stop  with  small  opening  will  be  proper. 

A  great  mistake  is  often  made  by  those  who  interest  themselves 
in  photography,  in  practising  too  much  economy  in  their  lenses. 
One  lens  cannot  be  made  to  do  the  work  of  another,  except  at  a 
sacrifice  of  excellence  of  result.  Every  lens  has  a  certain  size  of 
picture  for  which  it  is  suited  ;  if  used  for  a  smaller  size,  it  will 
give  a  less  angle  of  view,  and  work  more  slowly,  than  the  lens 
made  for  that  size;  if  strained  to  cover  a  larger  plate  than  that 
which  the  maker  intended,  a  sufficient  sharpness  of  focus  can 
only  be  got  by  using  too  small  a  stop.  And  the  beginner  cannot 
too  soon  learn  what  is  too  often  overlooked,  that,  where  solid 
bodies  are  to  be  depicted,  a  stop  of  a  fair  size  is  essential  if  the 
best  effects  are  desired.  It  is  only  where  flat  objects,  such  as 
maps,  engravings,  or  plans,  &c.,  are  to  be  copied,  that  small  stops 
are  right. 

If  the’ student  intends  at  first  to  provide  himself  with  one  lens 
only,  that  had  probably  better  be  a  Steinheil  aplanatic.  This 
and  the  Dallmeyer  “  rapid  rectilinear”  are  the  nearest  approaches 
to  a  universal  lens  that  we  have. 

In  commencing  photographic  work,  the  student,  whether  he 
intends  devoting  himself  chiefly  to  portraiture  or  to  landscape 


SELECTION  OF  MATERIALS. 


11 


work,  whether  as  amateur  or  professional  photographer,  will  find 
it  most  convenient  to  begin  by  taking  views,  or,  in  other  words, 
he  will  point  his  camera  out  of  the  windows  and  practise  on 
whatever  scene  presents  itself.  He  will  endeavor  in  this  way, 
firstly,  to  learn  to  make  clean  work,  that  is,  to  get  negatives  free 
from  failures,  such  as  stains,  fog,  comets,  &c.,  and  secondly,  to 
secure  harmonious  effects.  The  first  will  be  soon  accomplished, 
but  to  obtain  the  latter  in  a  good  degree  will  require  effort  and 
experience.  The  high  lights  must  be  dense  enough  not  to  print 
through  before  the  shadows  are  dark  enough,  and  there  must  be 
detail  everywhere.  That  is,  the  high  lights  must  never  show  a 
flat  white  surface,  but  must  be  relieved  by  faint  half  tint,  except, 
perhaps,  in  some  very  minute  portion.  The  shadows  must  not 
show  a  black  mass,  but  the  shape  and  form  of  the  objects  in 
shadow  must  be  everywhere  perceptible. 

Portraiture  may  next  be  attempted,  and,  in  default  of  a  sitter, 
a  white  plaster  bust  may  be  used,  with  different  colored  draperies. 
A  white  bust  with  black  drapery  makes  a  very  difficult  subject, 
and  to  obtain  at  once  a  well-shaded  face  and  preserve  the  folds 
in  the  drapery,  will  be  no  easy  task,  but  will  afford  excellent 
practice. 

Care  and  cleanliness  in  the  operations,  and  a  thoughtful  and 
close  study  of  results,  and  comparison  with  their  cause,  will  ac¬ 
complish  more  in  a  month,  than  rapid,  careless  work  in  two  or 
three. 

In  undertaking  landscape  photography ,  it  is  not  well  to  begin 
with  views  too  small  or  too  large.  The  smaller  the  pictures  are, 
the  more  easily  they  are  taken  in  every  respect ;  difficulty  in¬ 
creases  vastly  with  the  dimensions.  On  the  other  hand,  small 
prints  are  apt  to  be  too  trifling  and  insignificant  to  repay  for  the 
trouble  expended  upon  them.  Therefore  the  beginner  will  do 
well  to  start  with  “half  size”  plates,  and  go  from  that  to  whole 
size,  after  becoming  perfectly  familiar  with  all  the  manipulations. 
Eventually  he  will  probably  prefer  to  advance  to  8  x  10  and  per¬ 
haps  larger  work.  Generally  speaking,  the  most  artistic  effects 
are  got  with  plates  of  from  6Jx  8J  up  to  12  x  14.  Larger  prints 
are  apt  to  be  less  pleasing,  however  technically  perfect.  It  is  no 
advantage  whatever  to  have  a  lens  embrace  an  unnecessarily  wide 
angle,  except,  indeed,  where  architectural  objects  have  to  be 


12 


INTRODUCTION  TO  PHOTOGRAPHY. 


taken  in  positions  where  the  photographer  cannot  recede  beyond 
a  certain  point.  An  angle  of  50°  to  60°  is  generally  best. 

In  undertaking  portraiture ,  the  beginner  will  naturally  (after 
haying  just  practised  as  above  explained)  commence  with  card 
portraits.  For  this  work  a  “  card  lens”  will  be  wanted,  which  is 
simply  a  small-size  portrait  lens.  Of  these,  the  French  “  Jamins” 
are  the  lowest  in  price  ;  they  are  often  very  fair  in  their  perform¬ 
ances,  though  not  equal  to  the  best  English,  American,  or  German 
lenses. 

Lenses  should  be  kept  with  the  greatest  care — never  wiped 
with  anything  except  clean,  soft  old  linen  cambric,  and  even  with 
this  only  when  necessaiy.  The  exquisite  polish  on  the  surface  is 
of  the  highest  importance,  and  it  is  easily  injured. 

Do  not  begin  by  buying  second-hand  lenses,  but  go  to  respon¬ 
sible  dealers  and  purchase  the  work  of  makers  of  reputation. 

In  choosing  amongst  a  number  of  lenses  by  the  same  maker, 
view  a  piece  of  perfectly  white  paper  through  the  lens,  holding 
the  latter  close  to  it.  If  the  appearance  shows  that  the  glass  of 
which  the  lens  is  made  has  any  color,  especially  if  that  color  be 
brownish,  the  lens  should  be  rejected:  it  may  be  expected  to  be 
slow.  So,  too,  if,  when  carefully  examined  by  reflected  light,  it 
shows  any  striae,  or  hair-like  lines.  Yery  small  bubbles,  or 
white  spots,  if  not  exceeding  one  or  two,  are  unimportant,  and 
often  occur  in  excellent  lenses,  though,  of  course,  they  are  better 
absent,  and,  indeed,  are  rarely,  if  ever,  found  in  lenses  of  the  best 
makers. 

These  brief  remarks  are  perhaps  as  much  as  the  beginner  can 
advantageously  act  upon.  Other  points  will  be  explained  later. 

£  2.— Selection  of  Camera. 

Without  a  thoroughly  good  camera,  no  first-rate  work  can  be 
done,  and  the  beginner  cannot  make  a  greater  mistake  than  that 
of  purchasing  a  cheap  one.  Any  camera  that  is  not  thoroughly 
good  is  absolutely  worthless. 

A  camera  is  to  be  tested  as  follows: — 

1.  Observe  if  all  the  wood-work  is  sharply  cut  and  closely 
fitted. 

2.  Try  the  rack  and  pinion  movement,  to  notice  that  it  works 
easily  and  regularly,  and  not  by  jerks. 

3.  Eack  the  back  forwards  until  all  the  bellows  body  is  closed 


SELECTION  OF  MATERIALS. 


13 


Fie.  1. 


1 

'A 

LIT - - 7/ 

A 

m 

IB 

...  sJ 

in  ;  then  continue  to  rack  up  till  the  back  wood- work  just  comes 
into  contact  with  the  front.  Observe  attentively  if  this  contact 
takes  place  everywhere  at  once — top,  sides,  and  corners.  If  it 
does  not,  the  camera  is  worthless,  for  the  sensitive  plate  will  in 
such  a  case  not  occupy  a  position  perpendicular  to  the  optical 
axis  of  the  instrument. 

4.  These  points  having  all  been  found  satisfactory,  it  remains 
to  ascertain  whether  the  sensitive  plate,  when  in  place,  occupies 
the  exact  position  of  the  focussing  screen  of  ground  glass. 

This  is  the  most  essential  point  of  all,  and  is  precisely  that  in 
which  cameras,  even  of  good  makers,  are  apt  to  be  defective. 
The  fault,  if  it  exists,  is  easily  detected  with  a  little  attention. 

Take  a  piece  of  plate  glass  of  the  size  which  the  dark  slide  is 
intended  to  carry,  set  it  in  place,  close  the  door,  set  the  slide  on 
the  table,  door  undermost,  and  draw  out 
the  shutter.  Lay  across  the  middle  of  the 
slide  a  perfectly  flat  and  rigid  ruler,  a 
draughtsman’s  straight  edge,  or  a  long, 
thick,  narrow  piece  of  plate  glass.  Take 
a  piece  of  smooth  hard  card,  rest  one  end 
of  it  on  the  plate-glass,  pressing  the  side 
close  up  to  the  ruler,  and  with  a  sharp 
hard  pencil  draw  a  hair-line  where  the  card 
touches  the  ruler.  Next  repeat  this  exactly 
with  the  focussing  slide,  ground  side  of  the 
glass  uppermost.  If  the  camera  is  well 

made,  the  two  hair-lines  will  exactly  coincide  to  make  but  one. 
If  they  do  not,  the  camera  will  require  to  be  fitted  over  again  by 
the  maker.  Care  and  attention  are  necessary  to  make  this  trial 
effectual,  but  it  is  essential  to  make  it  with  every  new  camera. 

An  absolute  coincidence  of  the  two  lines  mus.t  be  insisted  on. 
At  the  same  time,  the  experimenter  must  be  sure  that  he  is  doing 
the  measuring  correctly,  and  not  producing  an  apparent  discord¬ 
ance  by  careless  manipulation. 

The  next  point  requiring  attention  will  be  the  inside  of  the  door 
of  the  slide.  This  is  alwaj^s  blackened  in  order  that  the  light 
which  passes  through  the  sensitive  plate  during  exposure  may 
not  be  reflected  back  upon  it,  but  this  blacking  is  often  very  in¬ 
sufficiently  done.  It  is  not  sufficient  that  the  surface  be  perfectly 
black,  it  must  also  be  perfectly  dead ,  must  have  no  appearance 


The  bottom  of  the  card  A  rests 
on  tlie  glass,  the  side  rests 
against  the  ruler  B  0,  aud  the 
pencil  line  is  drawn  where  the 
edge  B  0  touches  the  card  A. 


14 


INTRODUCTION  TO  PHOTOGRAPHY. 


whatever  of  shining  when  held  with  the  light  falling  upon  it  in 
any  direction. 

If  any  reflection  is  visible,  and  the  maker  be  accessible,  he 
should  be  required  to  render  the  surface  perfectly  dead.  If  the 
owner,  however,  finds  it  necessary  to  attend  to  this  himself,  he 


can  mix 

Powdered  gum  arabic 

Brown  sugar . 

Fine  lampblack  .... 

.  1  drachm. 

•  •  •  I  “ 

.  drachms. 

and  rub  them  well  together  with  a  little  hot  water  to  a  thick 
paste.  This  is  to  be  applied  with  a  flannel  rag,  and  rubbed  in 
well  and  evenly.  But  if  the  black  appears  to  have  been  origi¬ 
nally  applied  in  the  form  of  black  varnish,  it  will  be  well  to 
remove  this  polish  in  a  great  measure  by  rubbing  with  a  rag 
moistened  with  a  mixture  of  alcohol  and  ether.  If  the  above 
mixture  shines  when  dry,  there  was  too  little  lampblack.  If  it 
soils  the  finger  when  rubbed,  too  much. 

Carriers  are  small  frames  constructed  to  enable  one  with  any 
given  camera  and  slide  to  take  a  smaller  plate  than  the  proper 
plate  of  the  camera ;  large  cameras  are  often  supplied  with  a  set 
of  these  to  enable  the  owner  to  take  a  whole  series  of  sizes  with 
the  same  instrument.  They  are  certainly  very  convenient ;  they 
have  the  objection,  however,  that  they  sometimes  yield  a  little 
to  the  pressure  of  the  spring  of  the  back  of  the  slide,  and  allow 
the  plate  to  advance  too  near  the  point,  by  a  little  distance, 
which  may,  however,  displace  the  focus.  Therefore  the  above 
system  of  testing  should  be  repeated  with  each  carrier.  This 
method  has  the  advantage  that  the  plates  receive  the  same  pres¬ 
sure,  and  are  under  exactly  the  same  conditions,  as  when  receiv¬ 
ing  the  image. 

Of  course,  in  testing,  the  plates  set  into  the  slides  must  be  per¬ 
fectly  flat,  or  erroneous  indications  will  inevitably  result. 

Although  carriers  will  be  often  useful,  yet,  as  far  as  practi¬ 
cable,  it  will  be  better  to  use  the  slide  with  the  size  of  plate 
for  which  it  was  made. 

Prevention  of  Stains. — Stains  often  occur  from  the  absorption 
of  more  or  less  decomposed  nitrate  of  silver  from  the  slide,  left 
there  on  occasions  of  previous  use.  Saturating  the  whole  inside 
of  the  slide  with  some  repellant  substance  has  been  found  useful 
as  a  preventive.  Paraffine  or  lard  may  be  used.  If  paraffine  be 
used  it  must  be  melted  and  the  different  parts  of  the  slide  plunged 


SELECTION  OF  MATERIALS. 


15 


in  successively.  Lard  has  the  advantage  that  it  may  be  rubbed 
in  cold.  Either  the  application  should  be  made  when  the  slide 
is  new,  or  it  should  be  well  washed  and  all  old  stains  scraped 
carefully  away.  If  paraffine  be  used,  each  portion  of  the  holder 
should  remain  in  it  about  ten  minutes,  that  it  may  be  properly 
absorbed. 

The  Cut-off. — All  slides  should  have  a  cut-off,  a  wooden  spring 
inside  the  slit  through  which  the  shutter  passes,  and  which  closes 
the  opening  light  tight  when  the  shutter  is  withdrawn. 


g  3. — Selection  of  Stand. 

For  out-door  work,  a  folding  tripod  is  employed.  For  in-door 
work  many  forms  are  in  use.  Those  in  which  the  table  is  sup¬ 
ported  by  a  single  cylindrical  stem  are  very  objectionable,  for 
want  of  steadiness.  The  most  absolute  steadiness  is  requisite, 
and  a  large  proportion  of  the  stands  in  the  market  fail  to  fulfil 
this  requirement.  A  stand  cannot  be  judged  if  almost  unloaded. 
Place  a  heavy  camera  on  it,  strike  it  a  gentle  blow,  and  observe 
if  any  vibration  follows. 

2  4.— Selection  of  Chemicals. 

Few  photographers  have  sufficient  chemical  knowledge  to  be 
able  to  apply  tests  of  purity  to  their  chemicals.  Perhaps  the 
very  best  advice  that  can  be  given  to  a  beginner  is  to  observe 
who  amongst  his  friends  is  most  regularly  and  completely  suc¬ 
cessful,  and  then  to  obtain  materials  from  the  same  place.  In 
fact,  the  demands  of  photography  are  now  so  enormous,  that  good 
materials  can  be  obtained  almost  anywhere.  The  substance  most 
likely  to  give  trouble,  in  the  hands  of  a  learner,  is  nitrate  of 
silver.  This  last  should  always  be  purchased  prepared  expressly 
for  photography — never  from  the  druggist.  Without  the  best 
and  purest  neutral  nitrate,  the  negative  bath  cannot  be  expected 
to  work  well. 

The  same  remark  is  to  be  made  respecting  alcohol  and  ether, 
which  are  needed  of  the  very  best  quality  and  higher  grade  than 
usually  sold  by  even  the  best  druggists.  The  photographer  will 
need  to  have  alcohol  and  ether  always  at  hand  to  thin  his  collo¬ 
dion  with ;  for,  after  coating  a  plate,  the  excess  of  collodion  that 
is  poured  off  (into  a  separate  bottle)  is  always  much  thicker  than 


16 


INTRODUCTION-  TO  PHOTOGRAPHY. 


the  stock  in  the  bottle,  and  will  probably  need  to  be  thinned  as 
well  as  filtered  before  using  again.  This  thinning  work  needs  to 
be  done  chiefly  with  ether,  sometimes  with  the  addition  of  a  little 
alcohol. 


§  5.— Selection  of  Glass  for  Negatives. 

Of  all  matters  connected  with  photography,  the  selection  of  the 
glass  is  that  which  is  most  habitually  overlooked. 

Plate  glass  has  some  evident  advantages  over  blown.  Its  sur¬ 
face  is  a  true  plane;  the  material  of  which  it  is  made  is  generally 
whiter,  and  it  is  free  from  blebs  and  other  faults  and  irregularities. 
On  the  other  hand,  it  is  found  that  the  artificial  surface  of  the 
plate  glass,  produced  by  polishing,  does  not  hold  the  collodion 
and  varnish  so  well  after  a  lapse  of  years  as  the  natural  surface 
of  the  blown,  and  that  with  time  the  film  is  more  apt  to  crack 
and  suffer.  The  surface  of  plate  glass  is  also  more  porous  than 
the  natural  surface  of  blown  glass,  and  holds  back  stains  more 
strongly. 

In  consequence  of  the  high  price  of  plate  glass  in  America, 
blown  glass  is  almost  exclusively  used.  But  in  this  blown  glass 
there  is  great  variety  of  quality. 

1.  A  good  surface,  free  from  knots  and  blebs,  is  important,  and 
no  glass  that  has  not  this  characteristic  should  be  employed.  A 
smooth  collodion  film  cannot  be  got  on  an  irregular  surface. 

2.  Glass  varies  greatly  in  thickness.  It  is  a  great  advantage  to 
have  stout  glass ;  the  loss  from  breakage  of  negatives  in  the 
printing-frames  is  less,  and  the  operator  may  venture  to  apply  a 
strong  pressure  in  his  frames  where  his  glass  is  strong :  he  thereby 
gets  a  sharper  and  cleaner  print. 

3.  Blown  glass  varies  extremely  in  curvature.  Much  of  it  is 
very  flat;  much,  again,  greatly  curved.  All  that  is  much  curved 
should  be  rejected.  See  also  Part  III.,  Chap.  IY. 


MAKING  THE  NEGATIVE. 


17 


CHAPTER  II. 

MAKING  THE  NEGATIVE. 

§  1. — Absolute  Cleanliness. 

All  photographic  work  depends  upon  the  delicate  turning  of 
nicely-balanced  affinities,  which  a  slight  alteration  of  the  condi¬ 
tions  may  completely  reverse.  It  is  necessary,  therefore,  that  the 
operator  should  not  only  follow  closely  the  directions  given,  but 
that  he  should  learn  to  constantly  maintain  a  perfect  cleanliness. 

All  the  vessels  which  he  uses  must  be  irreproachably  clean ; 
and,  as  far  as  practicable,  each  should  be  restricted  to  some  par¬ 
ticular  use,  so  that  if  slight  vestiges  of  substances  escape  the 
attention,  such  may  be  less  hurtful.  The  hands,  especially,  must 
be  constantly  washed  ;  there  is  no  way  in  which  small  portions  of 
material  are  so  readily  transferred  as  by  adhesion  to  the  fingers. 
In  all  these  respects  too  much  precaution  cannot  be  taken,  and 
many  failures,  perfectly  unaccountable  to  the  beginner,  may  be 
traced  to  trifling  neglects  of  this  sort.  Nothing  will  so  well 
repay  its  trouble  as  a  systematic  and  invariable  attention  to  hav¬ 
ing  the  hands  and  all  the  utensils  clean  beyond  suspicion. 


§  2. — Preparing  the  Glass. 

Unless  the  glass  be  perfectly  clean,  a  regular  development  can¬ 
not  be  hoped  for.  Perhaps  the  best  method  of  cleaning  glass  is 
one  introduced  into  photography  by  the  writer  a  few  years  ago, 
and  which  has  since  been  extensively  used. 

Provide  a  large  glass  pan,  in  which  make  a  mixture  in  the 
following  proportions : — 

Bichromate  of  potash . 2  ounces. 

Sulphuric  acid . 3  fluidounces. 

Water . 25  fluidounces. 

Place  the  pieces  of  glass  in  the  pan  alternately,  one  at  each  end, 
so  that  their  ends  shall  overlap  a  little,  and  allow  the  fr^e  pas¬ 
sage  of  fluid  between  them.  For  new  glass  half  a  day  will  be 


18 


INTRODUCTION  TO  PHOTOGRAPHY. 


sufficient  to  destroy  the  greasiness.  Old  glass  that  has  been  used 
before,  should  have  a  day,  and,  if  it  has  been  varnished,  even 
longer,  or  a  mixture  containing  only  half  the  above  proportion 
of  water. 

So  long  as  this  bath  is  yellowish-brown,  it  is  active.  When  it 
acquires  a  violet  color,  it  is  spent ,  and  will  want  renewing. 

After  a  suitable  immersion  in  the  cleaning  bath,  place  the 
glasses  one  by  one  in  a  pan  under  a  water-faucet,  and,  as  fast  as 
the  water  fills  the  pan,  lift  one  end,  and  empty  it.  Repeat  this 
half  a  dozen  times  at  least.  Then  take  up  the  first  plate,  let  the 
stream  of  ivater  run  some  seconds ,  first  on  one  side ,  then  on  the  other, 
until  every  possible  trace  of  the  cleaning  bath  is  removed,  and 
then  rub  dry  with  soft  blotting-paper — not  with  cotton  rags,  as 
so  universally  directed.  Cloths  always  leave  fluff,  which  has  to 
be  carefully  brushed  away  afterwards — paper  does  not. 

It  is  usual  to  roughen  the  edges  of  the  plates,  and  thus  diminish 
the  chances  of  having  the  film  slip  off  during  the  work,  and  also 
to  lessen  the  risk  of  cutting  the  fingers.  A  coarse  file  is  com¬ 
monly  used,  but  the  writer  greatly  prefers  a  coarse  whetstone, 
such  as  is  used  for  sharpening  scythes.  It  cuts  faster  and  more 
evenly,  doing  better  work  in  less  time,  and  is  good  until  wholly 
worn  away,  whereas  the  file  quickly  becomes  clogged  and  smooth. 
The  whetstone,  or  file,  is  to  be  drawn  three  or  four  times  along 
each  edge,  holding  it  so  that  it  shall  rest  more  on  the  face  than 
on  the  edge.  The  roughing  should  precede  the  cleaning.  After 
cleaning  the  glass  must  be  handled  as  little  as  possible ;  its  face 
must  never  be  touched  by  a  finger,  or  there  will  probably  be  a 
finger  mark  developed  on  the  negative.  Glass  when  cleaned 
should  be  laid  away,  each  piece  in  a  fold  of  soft  clean  blotting- 
paper,  in  which  it  may  lie  even  for  months  without  injury,  if  set 
in  a  box  kept  out  of  the  reach  of  dust  and  vapors.  The  writer 
has  used  glass  which,  after  cleaning  with  the  bichromate  bath, 
had  been  kept  eighteen  months;  it  gave  good  results.  When 
glass  is  to  be  kept  for  more  than  a  few  days,  it  should  rest  on  its 
edges,  and  not  lie  flat,  otherwise  there  is  a  possibility  (the  writer 
has  seen  this  happen)  that  folds  in  the  paper  between  two  sheets, 
may  show  in  the  development. 

Nitric  acid  may  be  used  for  cleaning,  or  caustic  alkali ;  but  the 
above  is  not  only  the  easiest  and  most  economical,  but  is  perhaps 
the  only  one  with  which  an  old  picture  never  reappears  in  the 
development  of  a  new  one. 


MAKING  THE  NEGATIVE. 


19 


Plates  that  have  been  varnished  are  necessarily  more  difficult  to 
clean.  They  will  need  a  stronger  bath  and  a  longer  immersion 
in  it.  Or  the  varnish  may  be  easily  and  completely  removed  by 
soaking  in  a  bath  of  caustic  soda.  It  is  best  to  wait  till  a  quan¬ 
tity  accumulate,  and  then  to  dissolve  a  pound  of  “  concentrated 
lye”  in  a  half  pailful  of  hot  water,  and  put  the  plates  in,  one  by 
one,  leaving  them  in  till  they  easily  rub  clean ;  after  rinsing  off, 
put  them  into  the  bichromate  bath  for  a  few  hours.  When  com¬ 
mon  photographic  glass  is  used,  varnished  plates  scarcely  repay 
for  the  trouble  of  cleaning,  especially  as,  if  the  cleaning  is  not 
done  carefully,  the  negatives  will  not  be  satisfactory. 

§  3. — The  Negative  Bath. 

'  Of  all  that  the  photographer  works  with,  nothing  exceeds  in 
importance  the  negative  bath.  Its  preparation  is  exceedingly 
easy,  and,  if  thoroughly  good  nitrate  of  silver  be  used,  it  cannot 
fail  to  work  well,  if  no  mistake  or  oversight  has  been  made  in 
its  preparation. 

A  vertical  glass  lath  is  to  be  procured ;  there  is  none  other  which 
is  perfectly  safe.  In  a  porcelain  bath,  if  there  is  the  slightest 
flaw  in  the  glazing  inside,  the  solution  will  penetrate  it,  and 
gradually  saturate  the  whole  of  the  porous  biscuit  which  makes 
the  body  of  the  vessel,  between  the  inside  and  outside  glazing. 
This  not  only  involves  a  great  loss*  of  expensive  silver  solution, 
but  after  a  time  the  outside  glazing  also  probably  cracks,  and 
some  day  the  operator  finds  his  bath  empty.  In  many  cases 
porcelain  baths  last  for  years,  but  there  is  never  a  certainty  about 
them,  as  there  is  with  glass.  The  “photographic  ware”  has  been 
much  complained  of  in  the  same  way. 

A  glass  bath  requires  to  be  supported  in  some  way,  and  the 
simplest  is  to  place  it  in  a  box  sufficiently  wide  to  give  the  bath 
a  proper  inclination,  laying  a  wooden  or  pasteboard  cover  over 
it,  when  not  in  use,  to  exclude  the  dust;  or  boxes  may  be  pur¬ 
chased  provided  with  covers,  and  with  an  iron  foot  at  the  back 
to  enable  the  box  to  stand  at  a  proper  inclination  (see  beyond. 
Fig.  6,  p.  24). 

A  “whole-size”  bath,  for  plates  6Jx8£,  will  be  found  a  con¬ 
venient  one  for  the  beginner,  as,  even  if  much  smaller  plates  are 
worked  with,  it  is  not  worth  while  to  use  a  smaller  bath — it  holds* 
too  little  solution  and'  changes  too  rapidly.  The  “  whole-size” 


20 


INTRODUCTION  TO  PHOTOGRAPHY. 


baths  require  about  25  ounces  of  solution  to  charge  them.  This 
solution  is  to  be  made  as  follows : — 

Dissolve  2  ounces  of  nitrate  of  silver  in  25  ounces  of  water, 
which  need  not  be  distilled  water.  Leave  the  solution  in  a  glass 
bottle  in  the  sunlight  for  several  hours,  or  in  cloudy  weather  for 
a  day  or  two  near  a  southerly  window.  Separate  this  into  two 
equal  portions.  Take  3  grains  of  iodide  of  potassium  or  iodide 
of  ammonium,  dissolve  it  in  a  few  drops  of  water,  and  pour  it 
into  one  of  the  halves ;  stir  up  well  and  let  stand  half  an  hour, 
or  longer.  Filter  the  other  half  into  a  clean  bottle,  and  then  filter 
into  it  the  second  half,  that  to  which  the  iodide  of  potassium  was 
added. 

Observe:  The  two  portions  are  not  to  be  mixed  until  after  they 
are  filtered,  and  the  portion  to  which  the  iodide  was  added  is  to 
be  filtered  last ,  if  the  same  filter  be  used  for  both. 

Next,  take  a  clean  six-ounce  stoppered  vial;  place  in  it  one 
fluidrachm1  of  pure  nitric  acid,  fill  it  up  with  water,  and  label  it 
u  Dilute  nitric  acid,  ten  minims  to  the  ounce.”  To  the  twenty- 
five  ounce  bath  add  one  fluidrachm  of  this  dilute  acid. 

If  this  does  not  prevent  fogging,  the  fault  is  probably  in  the 
collodion.  It  will  therefore  be  advisable  to  add  to  it  enough 
tincture  of  iodine  to  bring  it  up  to  a  light  sherry  wine  color. 
Tincture  of  iodine  (which  must  not  be  confounded  with  “  Lugol’s 
Solution”)  may  be  purchased  ready  made,  or  be  prepared  by  dis¬ 
solving  a  quarter  of  an  ounce -of  iodine  in  four  ounces  of  alcohol ; 
it  should  be  prepared  and  kept  on  hand,  as  it  does  better  after 
standing  for  a  time.  If  with  a  collodion  of  a  sherry  wine  color, 
and  the  acidification  already  mentioned,  which  is  in  the  propor¬ 
tion  of  about  a  drop  of  nitric  acid  to  twenty  ounces  of  bath,  the 
fogging  continues,  it  shows  that  there  is  something  very  much 
wrong.  The  operator  may  try  the  effect  of  a  further  addition 
of  acid,  but  he  may  be  assured  that  either  he  has  made  some  mis¬ 
take,  or  is  working  with  bad  materials.  More  acid  may  force  a 
clean  picture,  but  will  fail  to  give  delicately  graded  shadows  and 
half  tints.  (See  also  Chapter  on  Failures.) 

The  negative  bath  should  always  be  kept  covered  to  exclude 
dust  and  dirt.  Constant  care  must  be  taken  to  let  no  extraneous 

1  The  photographer  should  provide  himself  with  graduated  measures  of  one 
pint,  of  two  ounces,  and  a  minim  glass  for  measuring  a  drachm  and  its  frac¬ 
tions.  One  minim  of  water  weighs  one  grain  nearly,  and  corresponds  approxi¬ 
mately  with  a  drop.  Sixty  minims  make  the  fluidrachm. 


MAKING  THE  NEGATIVE. 


21 


matter  get  into  it,  and  to  place  it  in  nothing,  and  nothing  in  it, 
that  is  not  perfectly  clean. 

When  the  hath  by  use  will  no  longer  work  well,  add  bicarbo¬ 
nate  of  soda  till  the  bath  just  turns  red  litmus  paper  blue,  boil  it 
down  to  one-half,  expose  it  for  a  day  to  sunshine,  filter,  dilute, 
and  add  just  enough  dilute  nitric  acid  to  get  a  clean  picture,  with 
a  collodion  known  beforehand  to  give  good  results.  Of  course 
nitrate  of  silver  must  be  added  from  time  to  time  to  keep  up  the 
strength,  which  is  rapidly  diminished  by  sensitizing  plates. 

Litmus  Paper  is  useful  to  indicate  whether  solutions  are  acid, 
alkaline,  or  neutral.  An  acid  solution  turns  blue  litmus  red ;  an 
alkaline  turns  red  litmus  blue ;  a  neutral  solution  is  without  influ¬ 
ence  on  either.  The  paper  should  be  cut  into  narrow  strips,  and 
kept  in  a  wide-mouthed  vial,  corked. 


4. — The  Developer. 


Make  the  developer  as  follows : — 


Proto-sulphate  of  iron 
Acetic  acid,  No.  8 
Alcohol 
Water 


400  grains. 
1^  ounce. 


The  developer,  if  kept  corked,  will  keep  for  a  couple  of  months. 
It  is  ready  for  use  as  soon  as  the  solution  of  the  sulphate  of  iron 
is  complete  and  the  whole  has  been  filtered.  As  it  grows  older 
it  becomes  reddish,  but,  so  long  as  kept  clear  by  filtration,  the 
reddening  is  rather  beneficial  than  otherwise. 


§  5. — Collodionizing  the  Plate. 


Holding  the  clean  glass  plate  by  pressing  a  finger  or  two  of 
each  hand  at  the  edges  of  the  plate  (the  fingers  must  never  touch 
the  face),  hold  it  up  to  the  light,  and  look  along  the  long  edge  to 
see  which  is  the  convex  and  which  the  concave  side.  The  choice 
between  these  is  a  matter  involving  a  variety  of  considerations 
which  will  be  stated  in  full  farther  on.  The  beginner  will  find 
it  best  to  generalize  as  follows :  for  portraits  and  for  buildings, 
coat  the  hollow  or  concave  side ;  for  landscapes,  the  convex  side. 
Next  brush  it  off*  with  a  broad  (two-inch)  soft  camel’s  hair  bpfish, 
which  must  be  kept  clean  and  free  from  dust,  and  be  used  for  no 
other  purpose.  It  should  not  even  be  left  in  damp  air,  or  it  may 


22 


INTRODUCTION  TO  PHOTOGRAPHY. 


leave  streaks  of  dampness  on  the  plate,  producing  stains  in  de¬ 
velopment.  It  is  an  excellent  plan  to  have  a  tin  box,  three  or 
four  inches  deep  and  an  inch  larger  in  breadth  and  length  than 
the  plates  which  thus  lie  in  it  between  folds  of  clean  blotting- 
paper.  Any  impurity  in  the  paper  is  transferred  infallibly  to  the 
glass.  The  writer  has  seen  glasses  between  which  newspapers 
had  been  laid,  take  off  a  complete  copy  of  the  print.  If  the 
glasses  remain  for  a  long  time  unused,  the  box  should  be  turned 
on  its  edge  that  the  plates  may  not  rest  on  each  other.  The  brush 
should  lie  in  this  box,  ready  for  use.  When  the  brush  is  drawn 
over  the  surface  of  the  glass,  it  should  slip  over  with  a  peculiar 
facility.  The  careful  operator  will  occasionally  notice  an  absence 
of  this  facility :  the  difference  is  so  slight  that  only  experience 
enables  one  to  appreciate  it,  but  when  once  observed  it  is  unmis¬ 
takable.  This  always  indicates  that  the  plate,  though  it  may 
have  been  well  cleaned,  has  not  been  sufficiently  rubbed  in  dry¬ 
ing.  A  quick  rubbing  with  clean  dry  blotting- 
paper  will  at  once  remove  this,  and  enable  the 
brush  to  pass  easily  and  lightly  over  the  sur¬ 
face.  But  rubbing  just  before  coating  is  always 
objectionable  :  the  glass  becomes  electrical,  and 
attracts  and  holds  motes  of  dust  that  may  be 
floating  through  the  air. 

After  brushing,  gently  but  thoroughly,  take 
the  plate  in  the  left  hand,  three  fingers  sup¬ 
porting  it  underneath,  the  thumb  pressing  on 
the  corner,  and  the  narrow  end  towards  you. 
Fold  up  a  piece  of  blotting-paper,  and  put  it 
between  the  bottom  of  the  plate  and  the  finger 
ends.  For  want  of  this  there  will  occasionally 
appear  curious  mottled  markings  at  the  points 
where  the  fingers  touch  the  under  side. 

Take  the  collodion  bottle  in  the  right  hand, 
having  previously  removed  the  cork  and  wiped 
the  lip  to  remove  dust  or  fragments  of  dried 
collodion.  {Never  neglect  this,  and  repeat  it 
between  every  plate.) 

Pour  the  collodion  slowly  and  steadily  on, 
letting  it  come  upon  the  plate  at  a  spot  a  little  further  from  you 
than  the  middle — say  equi-distant  from  the  end  and  the  two 


Fig.  2. 


Hold  at  3,  pour  ou  at 
A,  or  even  a  little  below 
the  dot,  and  off  at  4. 


MAKING  THE  NEGATIVE. 


23 


sides  (see  A,  Fig.  2).  Pour  on  till  the  pool  covers  rather  less 
than  half  the  plate. 

Incline  the  plate  till  the  pool  extends  itself  to  corner  No.  2 
(see  also  Fig.  3),  then  to  corner  No.  1  (see  Fig.  4).  Then  bring 
it  down  to  the  lower  end,  reaching,  however, 
corner  No.  3,  where  the  thumb  is,  before  cor¬ 
ner  No.  4,  at  which  it  is  to  be  poured  off  (see 
Fig.  5). 

This  is  all  to  be  done  quite  coolly,  and  yet 
without  loss  of  time.  The  collodion  must  go 
up  full  to  the  edge  of  the  plate  all  round,  and 
with  a  little  practice  this  is  accomplished  with 
great  ease  and  without  spilling  a  drop.  When 
the  operator  has  learned  to  do  this  with  ease, 
he  will  find  it  a  good  plan  to  send  bach  the 
collodion  from  4  to  1  before  pouring  off,  by  raising  corner  4  ;  as 
soon  as  the  wave  reaches  1,  corner  4  is  lowered  again,  and  the 
excess  poured  off  there.  This  makes  a  more  even  plate. 


Fig.  5. 


Fig.  4. 


It  is  best  not  to  pour  back  the  collodion  into  the  bottle  from 
which  it  came,  but  have  a  separate  bottle  ready,  uncorked. 

The  operation  of  pouring  off  requires  the  operator’s  best  atten¬ 
tion.  The  plate  must  be  slanted  but  very  little,  otherwise  tfhe 
collodion  runs  off  too  fast,  and  leaves  too  thin  a  film,  especially 
at  corner  No.  1.  At  the  same  time  the  operator  rocks  the  /plate, 
that  is,  turns  it  backwards  and  forwards,  one  quarter  round. 


24 


INTRODUCTION  TO  PHOTOGRAPHY. 


without  changing  the  inclination  (see  Fig.  5,  in  which  the  dotted 
line  shows  the  direction  taken  by  the  upper  left-hand  corner). 
If  this  be  neglected,  the  film  will  be  full  of  crapy  lines.  If  the 
plate  be  properly  rocked,  it  will  dry  as  smooth  as  the  glass  itself. 

The  writer  has  endeavored  here  to  give  as  clear  a  description 
of  the  method  of  collodionizing  a  plate  as  possible ;  at  the  same 
time  it  is  unquestionably  one  of  those  manipulations  which  it  is 
almost  necessary  to  see  done,  in  order  to  execute  properly  one’s 
self. 

No  formula  for  making  collodion  is  given  here.  The  beginner 
is  strenuously  advised  to  introduce  no  unnecessary  difficulty  by 
such  attempts,  but  to  procure  a  reliable  collodion  from  some  pro¬ 
fessional  photographer  or  trustworthy  dealer.  When  he  has 
mastered  the  manipulations,  he  may  advantageously  make  his 
own  collodion,  for  which  a  number  of  good  formulas  will  be 
given  further  on.  The  nitrate  bath,  the  developer,  and  the  fixing 
solution,  on  the  other  hand,  every  one  must  learn  to  prepare  for 
himself  from  the  outset. 

§  C. — Sensitizing. 

The  collodion  coating  quickly  sets — in  half  a  minute  or  less  in 
summer,  whilst  a  minute  may  be  necessary  in  winter.  The  be¬ 
ginner  may  judge  of  its  condition  by  gently  touching  it  near 
corner  No.  4  with  the  tip  of  the  finger ;  if  the  film  does  not  wet 


Fig.  6. 


the  finger,  but  receives  a  slight  depression  from  it,  which  remains 
after  the  finger  is  removed,  it  is  called  “tacky,”  and  is  now 
ready' for  immersion  in  the  bath.  Up  to  this  time  the  rocking 
motion  is  to  be  steadily  continued,  pausing  only  for  a  second,  if 


MAKING  THE  NEGATIVE. 


25 


necessary,  to  ascertain  the  condition  of  the  film.  When  this  has 
attained  the  proper  state  of  setting,  the  plate  is  to  be  rested  upon 
the  dipper  firmly  and  steadily.  The  operator  next  lowers  the 
dipper,  carrying  the  plate  with  it,  into  the  bath,  by  a  gentle,  con¬ 
tinuous,  and  uninterrupted  motion.  For  if  he  pauses  for  any 
fraction  of  time,  however  short,  the  part  of  the  film  which  at  that 
moment  corresponded  with  the  surface  of  the  bath  will  show  a 
distinct  line,  ruining  the  negative.  No  unnecessary  delay  should 
occur  in  putting  the  plate  in  the  bath,  or  the  risk  of  marbled 
stains  is  increased. 

Dippers  are  made  of  porcelain,  glass,  and  gutta-percha.  If  glass 
one§  could  be  got  of  a  right  pattern,  they  would  be  preferable, 
but  made  of  rods  they  are  too  fragile.  The  porcelain  are  good, 
and  the  gutta-percha  also,  provided  they  are  well  made,  and  con¬ 
sist  wholly  of  gutta-percha,  without  any  metallic  support  in  the 
centre.  The  porcelain  dipper  may  rest  in  the  bath  when  not  in 
use  ;  the  gutta-percha  dipper  must  never  be  left  in  the  bath.  The 
porcelain  is  the  best  and  safest.  It  has,  moreover,  this  recom¬ 
mendation,  that  if  the  plate  slips  off,  and  goes  down  to  the  bottom 
of  the  bath,  the  porcelain  dipper  can  be  easily  worked  under  it ; 
at  least  this  can  be  done  with  glass  baths,  the  bottoms  of  which 
are  always  a  little  rounded  and  hollow. 

If  the  plate  whitens  too  rapidly  in  the  bath,  it  is  an  indication 
that  it  has  waited  too  long  between  coating  and  immersing,  has 
become  too  dry,  and  its  sensitiveness  will  be  impaired.  The 
plate  should  wait  only  long  enough  to  prevent  splitting  in 
the  bath,  or  turning  mottled  in  the  part  least  dry,  both  of  which 
results  are  liable  to  follow  too  quick  an  immersion.  This  mot¬ 
tling  must,  however,  not  be  confounded  with  the  mottling  at  the 
pouring-off  corner,  which  results  from  a  collodion  too  thick,  or 
containing  too  large  a  proportion  of  alcohol,  or  alcohol  not  up 
to  95  per  cent. 

It  has  just  been  said  that  the  collodion  poured  off  from  the 
plate  must  be  received  into  a  different  bottle.  This  is  because  it 
is  apt  to  carry  with  it  motes  and  particles  of  dust,  which  appear 
on  the  next  plates.  The  collodion  is,  however,  perfectly  good 
for  subsequent  use,  but  it  will  not  only  need  to  be  filtered,  but 
thinned ,  because  the  evaporation  which  takes  place  from  the 
moment  that  the  collodion  is  on  the  plate,  causes  the  portions 
poured  oft*  to  be  much  thicker  than  the  original  stock.  As  the 
ether  evaporates  more  rapidly  than  the  alcohol,  the  thinning  is 
3 


26 


INTRODUCTION  TO  PHOTOGRAPHY. 


best  done  altogether  with  ether.  Neglect  to  thin  the  collodion 
will  produce  ridgy  plates,  and  especially  in  hot  weather,  tend  to 
the  production  of  small  transparent  spots,  known  as  pin-holes, 
appearing  anywhere  on  the  plate,  but  oftenest  in  the  dense  parts, 
particularly  in  skies  of  landscapes. 

(The  sources  of  trouble  in  photographic  operations  have  been 
collected  together  by  the  author,  and  will  be  found  in  a  “Chapter 
on  Failures,”  farther  on,  in  which  they  have  been  classified  for 
easy  reference  by  the  photographer  whenever  occasion  may  call 
for  it.) 

The  plate  having  been  placed  in  the  bath  will  be  left  quiet  for 
a  couple  of  minutes,  and  then  must  be  moved  up  and  down  from 
time  to  time ;  and  a  side  motion  is  also  beneficial,  especially  if 
the  plates  show  a  tendency  to  form  lines  in  the  direction  of  the 
dip,  a  trouble  of  which  much  complaint  has  been  made  by  some 
photographers,  though  it  has  never  been  experienced  by  the 
writer.  Until  the  plate  has  been  in  some  minutes  it  should  not 
be  raised  in  moving  so  as  to  be  partly  uncovered  by  the  silver 
solution. 

The  time  requisite  for  stay  in  the  bath  cannot  be  fixed  in 
minutes  with  any  positiveness,  as  it  depends  somewhat  on  the 
temperature,  the  nature  of  the  collodion,  and  the  condition  of  the 
bath.  From  three  to  five  minutes  is  about  the  time.  The  plate 
is  ready  when,  on  withdrawing  from  the  bath,  no  oily  lines  form 
on  the  surface,  but  the  whole  face  presents  a  uniform  moist  film. 
The  plate  should  never  be  left  longer  than  necessary  in  the  bath, 
as  by  so  doing  the  film  tends  to  dissolve,  thus  choking  the  bath 
with  excess  of  iodide,  and  rendering  the  plate  irregular.  Worse 
still,  there  is  a  great  tendency  in  such  plates  to  give  flat  and  dull 
images,  at  least  in  collodion  containing  bromides. 

There  is,  of  course,  always  a  little  latitude  allowable.  And  it 
is  to  be  remarked  that  a  plate  removed  from  the  bath  as 
soon  as  the  oily  streaks  are  gone  is  in  condition  to  give  the 
cleanest  plates;  if  left  a  little  longer,  it  gains  in  sensitiveness,  but 
also  there  is  a  little  more  tendency  to  veil. 

The  plate  is  now  to  be  removed  from  the  bath  and  rested  on 
several  thicknesses  of  soft  blotting-paper,  changing  its  position 
every  few  seconds,  until  it  no  longer  wets  the  paper.  A  thorough 
draining  in  this  way  is  very  important,  and  cannot  be  neglected 
without  danger  of  streaks  and  other  irregular  action.  At  the 
same  time  the  back  of  the  plate  is  to  be  carefully  wiped  dry  with 


MAKING  THE  NEGATIVE. 


27 


soft  paper.  This  wiping  and  thorough  draining  must  never  be 
omitted ;  neglect  of  these  precautions  will  tend  to  produce 
streaks  and  stains.  It  is  a  very  good  plan  to  keep  ready  pieces 
of  thick  soft  red  blotting-paper,  half  an  inch  smaller  than  the 
plate  all  round ;  and  after  it  has  been  wiped  clean  to  apply  one 
of  these  pieces  moistened  with  clean  water,  but  not  too  wet,  to 
the  back.  This  precaution,  though  recommendable,  has  not  yet 
come  into  general  employment.  Its  use  is  to  diminish  internal 
reflections  or  blurring ,  as  will  be  more  fully  explained  hereafter. 

In  all  these  operations  the  face  of  the  plate  must  never  be 
touched  by  the  fingers,  and  with  the  same  precaution  the  plate 
is  to  be  lifted  and  gently  set  into  its  place  in  the  dark  side,  taking 
care  that  the  shutter  is  in  its  place.  The  door  is  then  closed. 

From  the  time  that  the  plate  is  lifted  from  the  bath  the  same 
edge  must  carefully  be  kept  undermost ;  that  is,  the  side  which 
went  undermost  into  the  bath  must  be  kept  undermost — must  be 
that  which  rests  on  the  blotting-paper-^must  be  kept  undermost 
in  the  transfer  to  the  dark  slide,  and  the  slide  with  its  plate  in  it 
must  be  carefully  kept  with  that  edge  downwards,  not  only  during 
exposure,  but  in  carrying  backwards  and  forwards  and  up  to  the 
moment  of  development.  This  is  essential;  neglect  of  it  will 
almost  certainly  result  in  streaky  lines  and  irregular  deposits 
along  the  outside  of  the  plate,  running  up  in  places  some  distance 
into  the  plate.  If  the  small  size  of  the  bath  renders  it  necessary 
to  set  the  plate  in  end  down,  when  the  side  is  to  be  down  in  the 
slide,  the  plate  must  be  turned  immediately  on  taking  it  from  the 
bath,  and  the  draining  and  blotting  done  whilst  it  is  in  the  same 
position  which  it  is  to  have  in  the  slide.  In  this  way  no  harm 
results  from  the  change  of  position. 

Particular  descriptions  of  the  dark  room  and  glass  room  must 
be  omitted  for  the  present.  Here  it  is  sufficient  to  say  that  all 
the  operations  of  sensitizing  and  developing  must  be  performed 
by  yellow  light.  A  very  simple  way  of  converting  an  ordinary 
room  into  a  dark  room  for  photographic  work  consists  in  pro¬ 
curing  some  of  the  very  thickest  and  stoutest  brown  paper  made 
for  envelopes,  and  pasting  pieces  of  it  over  the  panes  of  the  win¬ 
dow  ;  a  great  deal  of  light  will  come  through  this,  sufficient  for 
all  the  operations,  and  yet,  if  the  paper  be  good  and  thick  and  of 
fine  grain  and  quality,  there  will  be  no  danger  of  fogging.  If, 
however,  the  sun  shines  directly,  at  times  of  the  day,  upon  the 
window,  it  will  be  well  to  have  a  buff  curtain  on  rollers  inside  the 


28 


INTRODUCTION  TO  PHOTOGRAPHY. 


window,  so  that  when  the  light  is  too  strong  it  may  be  properly 
tempered. 

If  the  room  used  as  a  dark  room  has  two  windows,  it  will  be 
found  preferable  to  cover  the  panes  of  one  only,  and  to  have 
closely  fitting  inside  shutters  to  the  other,  over  the  joints  of  which 
black  muslin  must  be  pasted  or  tacked.  In  this  way  the  room 
may  be  lighted  at  any  moment,  and  may  serve  for  other  uses  than 
merely  as  a  dark  room. 

However  the  dark  room  be  arranged,  provision  must  be  made  for 
its  thorough  ventilation ,  the  fumes  of  collodion  tending  to  produce 
headache,  nervous  exhaustion,  and  to  undermine  the  health. 
This  subject  will  be  recurred  to  hereafter;  it  should  never  be 
lost  sight  of  by  the  photographer  who  values  his  health. 

§  7. — Focussing, 

The  photographer  first- covers  the  camera  with  a  black  cloth, 
and  places  his  head  beneath  it.  The  cloth  should  be  ample  to 
exclude  all  white  light ;  even  a  few  scattered  rays  of  light  will 
greatly  diminish  the  brilliancy  of  the  image  as  seen  on  the  ground 
glass,  and  interfere  with  a  proper  judgment.  The  picture  should 
be  composed  and  arranged  with  the  largest  opening  of  the  lens, 
and  after  this  is  done  the  proper  stop  is  next  substituted  and  the 
focus  carefully  taken. 

Few  persons  have  unassisted  sight  so  sharp  as  to  enable  them  to 
take  a  thoroughly  good  focus,  although  a  delusion  to  the  contrary 
is  very  wide-spread.  It  is  always  better  to  examine  the  image  on 
the  ground  glass  through  a  microscope,  as  a  better  focus  can  be 
got  more  quickly,  and  with  less  strain  upon  the  eyes.  The 
microscope  should  consist  of  two  lenses  in  the  same  tube,  at  least 
an  inch  in  diameter.  The  difference  of  fatigue  to  the  eyes  in 
using  large  and  small  lenses  is  enormous.  A  magnifier,  with 
lenses  of  one  and  a  half  to  two  inches  in  diameter  is  the  best ;  its 
expense  is  small,  as  it  is  not  absolutely  necessary  that  the  lenses 
should  be  achromatized.  The  little  doublets  used  by  engravers 
are  good,  and  larger  ones  can  be  got  of  any  optician  of  the  same 
pattern.  The  writer  does  not  advise  the  system  of  focussing  on 
clear  glass  with  an  adjusted  eye-piece. 

The  operator  is  not  to  take  his  focus  on  any  point  of  the  picture 
indifferently,  but  according  to  the  following  rules: — 


MAKING  THE  NEGATIVE. 


29 


In  taking  a  single  portrait,  focus  on  the  face  as  the  most  im¬ 
portant  point. 

In  taking  two  heads  equidistant  from  the  centre,  focus  on 
either  head,  not  on  any  more  central  object. 

In  taking  a  group,  focus  on  one  of  the  heads  occupying  a  posi¬ 
tion  midway  between  the  centre  and  the  extremity  of  the  group. 

In  focussing  a  landscape,  care  must  be  taken  that  the  fore¬ 
ground  is  in  good  focus,  and  at  the  same  time  that  sufficient 
sharpness  is  preserved  all  over  the  picture.  The  largest  stop 
with  which  this  result  can  be  obtained,  must  always  be  used.  It 
is,  however,  not  necessary  that  very  distant  objects  should  be  as 
sharp  and  clean  cut  as  the  foreground  must  be;  to  accomplish 
this  would  require  the  use  of  a  stop  so  small  as  to  flatten  the 
whole  picture.  Many,  however,  do  this,  and  the  result  is  that 
their  pictures  have  no  effect  of  distance  or  atmospheric  per¬ 
spective.  On  the  other  hand,  if  the  focus  be  not  taken  with 
judgment,  the  result  will  be  a  failure.  A  swing  bach  (hereafter 
to  be  described)  aids  materially  in  getting  a  whole  view  into 
good  focus  with  a  large  stop. 

These  directions  are  important,  and  cannot  be  disregarded  with 
impunity.  Careless  focussing  is  almost  the  worst  fault  that  a 
photographer  can  have,  and  will  counteract  every  care  or  pre¬ 
caution  that  he  can  take  in  other  parts  of  the  process. 

Where  buildings  of  any  description  form  part  of  the  subject, 
it  will  be  necessary  to  level  the  camera ,  otherwise  the  perpen¬ 
dicular  lines  of  the  edifices  will  not  be 
perpendicular  in  the  negative,  but  will 
converge  or  diverge.  This  levelling  the 
camera  often  prevents  the  upper  part  of 
the  building  from  appearing  upon  the 
ground  glass.  Material  help  can  be  gained 
by  raising  the  sliding  front  (see  Fig.  7).  This, 
however,  must  be  done  with  circumspec¬ 
tion,  or  the  upper  corners  of  the  negative 
will  be  transparent  (and  print  black)  by 
being  outside  the  circle  of  light  given  by 
the  lens.  It  must  be  also  remembered  that 
the  definition  is  always  best  at  the  centre, 
that  when  the  lens  is  shifted  in  position  by 
raising  the  front,  the  upper  parts  of  the  objects  will  not  be  quite 
so  sharp  as  when  the  lens  is  in  its  usual  place ;  nevertheless,  the 


Fi s.  7. 


30 


INTRODUCTION  TO  PHOTOGRAPHY*. 


plan  is  a  useful  one.  The  swing-back  is  also  useful,  but  will  need 
an  intimate  acquaintance  with  photography-  to  avail  one’s  self  of 
it ;  its  operation  will  be  explained  hereafter. 

§  8. — Exposure. 

The  time  of  exposure  for  a  wet  plate  may  vary  from  a  fraction 
of  a  second  to  half  an  hour. 

With  a  portrait  combination,  medium  stop,  and  good  light 
from  three  to  fifteen  seconds,  or  even  more,  may  be  required. 
With  landscapes  taken  by  a  view  or  a  doublet  lens  and  medium 
stop,  from  ten  seconds  up  to  several  minutes  may  be  given,  ac¬ 
cording  to  the  light.  With  a  bright  light,  and  by  having  the 
chemicals  in  exact  order,  a  picture  may  be  got  in  a  fraction  of  a 
second  with  a  short  focus  lens,  using  a  large  stop.  The  operator, 
however,  will  do  well  to  leave  instantaneous  photography  until 
he  succeeds  regularly  and  without  difficulty  in  ordinary  ex¬ 
posures. 

The  slide  should  always  be  set  into  the  camera  steadily  and 
gently,  not  with  a  jerk  or  snap,  lest  any  dust  be  set  in  motion  and 
settle  on  the  sensitized  plate,  the  result  of  which  will  be  seen  in 
comets  or  pin-holes. 

§  9. — Development  and  Redevelopment. 

The  operator  brings  back  the  dark  slide,  without  loss  of  time, 
to  the  dark  room,  never  forgetting  for  an  instant  to  keep  that  part 
of  the  slide  down  which  was  lowest  in  the  camera,  and  in  all  pre¬ 
vious  stages.  Holding  the  slide  with  the  left-hand  edge  in  his 
left  hand,  he  opens  the  door  with  his  right,  places  his  thumb  on 
the  upper  edge  of  the  plate,  with  the  fingers  touching  it  lower 
down,  and,  by  inclining  the  slide  a  little  backwards,  brings  out 
the  plate.  This  is  now  transferred  to  the  left  hand,  always  keep¬ 
ing  the  lower  edge  downwards.  He  now  turns  the  plate  up  nearly 
to  a  horizontal  position  ;  a  proper  quantity  of  the  developer  (about 
an  ounce  for  a  whole-sized  plate,  or,  for  a  beginner,  a  little  more) 
has  previously  been  placed  in  a  suitable  glass  vessel — Fig.  8 
represents  a  good  shape;  this  the  operator  takes  in  his  right 
hand,,  and  holding  it  a  little  inclined,  and  at  the  upper  edge  of 
the  plate  near  the  left  hand,  pours  out  the  liquid,  at  the  same 
time  drawing  the  vessel  towards  the  right,  so  that  the  liquid  may 


MAKING  THE  NEGATIVE. 


31 


Fig.  8. 


spread  rapidly  and  evenly  over  tlie  whole  surface  of  the  plate. 
Some  dexterity  is  required  to  do  this,  except  with  very  small 
plates.  Just  as  the  developer  spreads  over  the  plate 
and  reaches  the  lower  edge,  the  plate  is  carried  to  a 
horizontal  position,  for  it  is  an  object  not  to  let  more 
than  can  be  helped  run  over.  The  developer  becomes 
mixed  on  the  surface  of  the  plate  with  the  bath  solu¬ 
tion  with  which  the  film  is  impregnated,  and  this  mix¬ 
ture  provokes  the  development.  If  much  is  wasted 
by  washing  over  the  side,  the  image  will  come  out  less  strong, 
and  a  redevelopment  will  be  more  likely  to  be  necessary. 

The  rapidity  of  development  under  the  action  of  the  developer 
will  depend  on  what  has  been  the  exposure.  If  the  image  flashes 
out  instantly,  the  exposure  has  been  too  long,  and  the  picture 
will  want  contrast.  If  the  picture  comes  out  slowly,  reluctantly, 
so  that  after  a  minute  or  two  only  the  strongest  marked  points 
of  the  subject  are  visible,  the  exposure  has  been  too  short,  and 
the  picture  will  probably  be  too  full  of  contrast,  wanting  in 
detail,  and  hard  and  blocky.  If  the  picture  soon  begins  to  show 
itself,  and,  instead  of  flashing  out  too  suddenly,  grows  steadily 
and  even  rapidly  in  strength,  a  good  result  may  be  anticipated. 
As  the  development  goes  on,  the  operator  inclines  the  plate  a 
little  in  different  directions,  so  as  to  render  the  developer  regular 
and  even  in  its  action.  When  the  plate  has  come  pretty  well 
out  the  operator  pours  off  the  developer  from  one  corner  into  its 
vessel  again,  and,  as  he  drains  the  last  drop,  he  raises  the  plate 
perpendicularly  between  himself  and  the  light,  and  judges  of  its 
strength  and  character.  If  these  appear  satisfactory,  he  stops  the 
operation  by  washing  off*  the  plate  ;  if  not,  he  pours  on  the  deve¬ 
loper  again  (provided  this  last  has  remained  active  and  clear), 
and  keeps  it  on  a  few  moments  longer.  But  if  it  seems  to  have 
ceased  its  effects,  and  still  more,  if  the  slightest  tendency  to  fog 
manifests  itself,  or.  if  the  developer  looks  in  the  least  muddy,  the 
operator  quickly  washes  the  plate,  and  if  on  a  further  careful 
inspection  he  finds  that  it  still  wants  strength,  he  proceeds  to 
redevelop. 

Care  will  always  be  needed  that  the  developer  is  used  in  suffi¬ 
cient  quantity  to  cover  the  plate  quickly  and  easily.  Too  much 
is  always  better  than  too  little,  though  with  too  much  developer 
the  silver  will  always  be  too  much  diluted  and  washed  away,  and 


32 


INTRODUCTION  TO  PHOTOGRAPHY. 


there  will  be  more  probability  of  a  redevelopment  being  needed. 
(Very  full  information  in  all  the  details  of  development  will  be 
found  in  the  second  part.) 

Another  point  will  require  special  attention.  The  developer 
is  apt  not  to  mix  easily  with  the  bath  solution  contained  in  the 
film  ;  as  long  as  the  plate  is  level  the  tendency  does  not  appear. 
But  when  the  plate  is  raised  to  judge  of  its  strength  by  looking 
through,  and  part  of  the  surface  liquid  drains  off,  the  indisposi¬ 
tion  to  mix  shows  itself  by  the  formation  of  oily  lines  resembling 
those  upon  a  plate  removed  too  soon  from  the  negative  bath. 
Now  these  oily  lines  that  form  on  the  plate  when  raised  to  look 
through,  consist  of  the  developing  liquid  which  collects  in  that 
form,  consequently  the  development  of  the  plate  goes  on  under 
these  lines,  and  checks  elsewhere.  There  results  a  set  of  streaks  on 
the  plate  that  wholly  ruin  it.  There  is  no  more  fruitful  origin 
of  trouble  to  beginners  than  this,  and  its  source  is  often  wholly 
•unsuspected.  Nor  is  it  easily  avoided.  If  the  negative  bath 
have  been  a  good  deal  used,  the  addition  of  alcohol  to  the  deve¬ 
loper  to  the  proportion  of  an  ounce  or  two  to  the  pint  will  some¬ 
times  help. 

Redevelopment  may  be  done  either  before  or  after  fixing,  the 
difference  is  but  slight  in  the  final  result ;  as  far  as  it  goes,  it 
may  be  stated  as  follows  :  If  the  contrasts  are  likely  to  be  a  little 
too  great,  or  tend  that  way,  redevelop  before  fixing ;  if  the  con¬ 
trasts  are  scarcely  sufficient,  fix  first  and  redevelop  afterwards. 
Not  much,  however,  in  the  way  of  a  curative  agency  can  be  ex¬ 
pected  in  this  way,  and  pictures  which  are  either  too  harsh  or  too 
uniform,  are  best  wiped  out  at  once  and  taken  over. 

The  operator  will  always  bear  in  mind,  in  deciding  when  his 
development  or  redevelopment  is  carried  far  enough,  that  the 
apparent  strength  of  the  picture,  as  he  then  sees  it,  will  be  con¬ 
siderably  reduced  in  the  operation  of  fixing,  and  for  this  he  must 
make  due  allowance. 

A  close  watch  must  be  kept  on  the  plate,  and  if  the  slightest 
tendency  to  form  oily  lines  shows  itself,  the  plate  must  be  in¬ 
stantly  held  under  the  tap,  or  better,  be  plunged  into  a  pan  of 
clean  water  ready  for  the  purpose.  And  if  it  proves  on  careful 
examination  to  want  density,  this  must  be  got  by  redevelopment. 

Negatives  that  come  out  of  the  right  strength  by  the  first  de¬ 
velopment  are  the  best.  If  under-exposed,  they  are  apt  to  become 


MAKING  THE  NEGATIVE, 


83 


hard  and  crude  in  the  process  of  redevelopment ;  and  if  over¬ 
exposed,  the  evil  is  incurable.  A  brilliant  print  can  only  be  got 
from  a  brilliant  negative.  Much  will  depend  upon  the  collodion, 
or,  rather,  the  pyroxyline  from  which  it  is  made.  Highly  sensi¬ 
tive  collodions,  and  those  newly  prepared,  are  more  likely  to 
need  redevelopment :  more  intense  pyroxylines  and  older  collo¬ 
dion  less  likely. 

Redevelopment  may  be  effected  in  various  ways.  The  most 
usual  is  with  pyrogallic  acid,  and  that  is  the  plan  which  I  shall 
here  describe. 

To  redevelop  with  pyrogallic  acid,  the  operator  keeps  in  a 
stoppered  vial  the  following  solution: — 


Nitrate  of  silver . 60  grains. 

Citric  acid . 120  “ 

Water . 6  ounces. 

And  in  a  well-corked  vial: — - 

Pyrogallic  acid . £  ounce 

Alcohol . 4  ounces. 


Both  these  solutions  will  need  filtering  ;  both  keep  for  months. 

When  the  iron  development  has  done  what  it  can,  and  before 
any  disposition  to  fog  sets  in,  the  plate  is  to  be  thoroughly  well 
washed  off.  In  a  convenient  developing  vessel  the  operator  puts 
water,  about  an  ounce  or  a  little  less  for  a  6^  X  8  J  plate,  and  pro¬ 
portionately  for  other  sizes.  He  next  adds  a  little  pyrogallic 
solution,  about  twelve  or  fifteen  drops  for  the  ounce  of  water, 
with  which  it  immediately  mixes.  He  then  adds  a  few  drops, 
say  fifteen  or  twenty,  of  the  silver  and  citric  acid  solution  to  the 
ounce  of  water,  mixes  well,  and  pours  the  mixture  over  the  plate. 
The  image  immediately  begins  to  grow  in  strength,  and,  by  keep¬ 
ing  the  silver  and  pyro  on,  any  desired  degree  of  strength  can  be 
obtained.  The  redeveloper  soon  darkens  to  a  wine  color,  and  in 
that  condition  its  action  is  still  powerful.  But  if  it  becomes  in 
the  least  muddy,  it  must  be  rapidly  washed  off  the  plate.  So 
long  as  the  solution  remains  transparent  and  bright,  even  if  port- 
wine  color,  it  is  not  easy  to  fog  the  picture.  Still,  even  the  pyro¬ 
gallic  developer  is  not  to  be  trusted  too  far,  or  fog  may  set  in  in 
brown  spots.  When  redeveloping  is  done  after  fixing,  the  hypo¬ 
sulphite  must  first  be  washed  off  most  thoroughly,  back  as/well 
as  front. 


34 


INTRODUCTION  TO  PHOTOGRAPHY. 


When  it  is  intended  to  redevelop  plates  that  have  been  fixed 
and  dried,  a  little  more  care  is  necessary.  It  is  best  to  redevelop 
in  a  pan.  And  as  there  is  here  more  danger  of  spotting  and 
staining,  it  is  best  to  add  a  little  acetic  acid  besides  the  citric. 
The  operator  watches  the  operation,  keeps  the  developing  bath 
continually  moving  by  tilting  the  pan,  and  examines  the  progress 
of  the  work  at  intervals.  Plates  after  drying  take  density  more 
slowly  than  when  redeveloped  immediately  after  the  first  develop¬ 
ment.  When  plates  have  been  allowed  to  dry,  and  are  afterwards 
found  to  need  redeveloping  with  pyro,  they  are  apt  to  show  a  ten¬ 
dency  to  split  in  drying  after  the  redevelopment ;  it  is  therefore 
a  good  plan  to  flow  them  over  with  the  following  solution:— 

Clean  gum  arabic . 2  ounces. 

Water . 20  “ 

Carbolic  acid . £  drachm. 

The  carbolic  acid  enables  the  gum  solution  to  be  kept  indefi¬ 
nitely  without  moulding  or  souring.  A  little  of  the  solution  is 
poured  over  the  plate,  worked  in  by  moving  the  plate  so  that  it 
shall  spread  over  the  whole  surface,  which  can  easily  be  judged 
of  by  catching  the  light  upon  it.  This  is  drained  off  by  holding 
up  the  plate,  and  the  operation  repeated  with  a  fresh  portion  of 
solution,  after  which  the  plate  is  reared  up  to  dry.  Different 
collodions  vary  very  much  as  to  tendency  to  split  in  drying,  and 
to  their  need  for  this  protection.  (This  operation  does  not  take 
the  place  of  varnishing ;  plates  that  have  been  gummed  must  be 
varnished  the  same  as  others.) 

A  pyrogallic  development  may  be  used  in  the  first  place  instead 
of  the  iron.  In  this  case  the  pyrogallic  acid  solution  is  added  to 
water,  about  eight  drops  to  the  ounce,  a  little  acetic  acid  is  added, 
and  the  mixture  is  poured  over  the  plate  as  it  leaves  the  frame. 
This  is  a  very  easy  development,  and  gives  bright,  strong  pic¬ 
tures.  But  the  iron  development  is  preferable,  because  softer 
pictures  are  got,  more  full  of  detail,  and  shorter  exposures  are 
sufficient. 

The  vessels  used  for  developing  must  be  kept  scrupulously 
clean.  If  the  remains  of  the  developer  be  left  in  them  a  few 
minutes,  it  becomes  turbid,  and  a  gray-black  precipitate  of  metal¬ 
lic  silver  collects  round  the  sides  and  bottom.  Any  of  this  left 
in  will  tend  to  render  the  next  lot  of  developer  muddy,  and 
therefore  must  be  completely  removed. 


MAKING  THE  NEGATIVE, 


35 


I  am  in  the  habit  of  keeping  beside  me  the  following  solution 
in  a  beaker  or  wide-mouthed  bottle : — 

Concent,  solution  bichromate  of  potash  .  .  .1  fluidounce. 

Sulphuric,  or  better,  hydrochloric  acid  .  .  £  “ 

Water . 3  fluidounces. 

It  is  only  necessary  to  pour  this  solution  into  the  dirtiest  de¬ 
veloping  vessel,  and  then  immediately  out  again,  when  it  will 
be  found  perfectly  bright  and  clean.  It  is  scarcely  necessary  to 
say  that  it  must  be  well  rinsed. 

The  same  solution  is  very  useful  for  removing  silver  stains 
from  the  fingers.  If  got  into  cuts  or  abrasions  of  the  skin,  it  is 
to  some  violently  irritating,  to  others  quite  indifferent,  except  a 
momentary  smarting.  It  is  much  preferable  to  the  use  of  cyanide 
of  potassium,  a  most  dangerous  chemical,  and  the  indiscreet  use 
of  which  is  injurious  to  health,  and  may  become  destructive  to 
life.  Or  they  may  be  rubbed  with  strong  tincture  of  iodine 
(alcohol  1  oz.,  iodine  40  grs.);  and  when  the  stain  has  become 
yellow  (not  before),  it  will  dissolve  in  a  strong  solution  of  hypo¬ 
sulphite  of  soda. 

Of  these  methods,  the  first  will  generally  prove  the  most  effi¬ 
cacious  ;  it  should  be  followed  by  washing  with  hyposulphite. 
All  silver  stains,  however,  should  be  attacked  before  they  are  set 
by  exposure  to  light,  otherwise  the  difficulty  of  getting  rid  of 
them  is  greatly  increased. 


|  10. — Fixing,  Washing,  and  Drying. 

The  negative  fixing-bath  consists  of  a  strong  solution  of  hypo¬ 
sulphite  of  soda,  in  the  proportion  of  five  or  six  ounces  to  the 
pint  of  water.  Some  pour  the  solution  over  the  plate  until  it  is 
clear.  But  this  involves  a  loss  of  time.  It  is  better  to  keep  the 
fixing-bath  in  a  horizontal  pan,  and  carefully  to  slide  the  nega¬ 
tive  into  it.  When  the  yellow  opaque  appearance  of  the  iodide 
and  bromide  has  completely  disappeared,  the  plate  is  fixed.  The 
same  bath  may  be  used  for  a  number  of  negatives,  but  should 
not  be  kept  too  long.  A  yellowish  feathery  appearance  through 
the  film  indicates  insufficient  fixing,  and  may  be  removed  by 
another  immersion  in  the  fixing-bath. 

The  plate  thus  fixed  is  to  be  set  under  a  tap  and  thoroughly 
washed  by  allowing  a  stream  of  water  to  fall  upon  it,  whilst  the 


36 


INTRODUCTION  TO  PHOTOGRAPHY. 


Fi°\  9. 


plate  is  supported  at  such  an  angle  that  the  ripple  is  seen  to 
spread  in  all  directions,  and  keep  the  water  in  continual  motion 
over  the  whole  surface  of  the  plate.  To  accomplish  this,  the 
plate  must  be  kept  in  such  a  position  that  the  stream  of  water 
which  falls  upon  it  will  flow  off  in  every  di¬ 
rection.  The  writer  finds  the  most  conve¬ 
nient  mode  of  accomplishing  this  to  consist 
in  having,  two  cones  of  zinc,  as  represented 
in  the  margin.  The  lower  and  larger  is  six 
inches  in  diameter  at  bottom,  and  five  at  top; 
stands  seven  inches  high.  The  upper  is  six 
inches  diameter  at  top,  three  at  bottom,  and 
five  inches  high.  Both  are  open  at  top  and 
bottom,  and  small  notches  are  cut  at  the  base 
of  the  larger.  The  negative  rests  on  the  upper  rim;  it  will 
be  found  easy  to  give  it  any  slant  in  any  direction,  and  with  the 
advantage  that  it  will  retain  that  position  with  entire  steadiness. 
After  setting  the  plate  upon  this  or  any  other  support  during  the 
washing,  the  operator  must  never  fail  to  catch  a  reflection  of  light 
upon  the  surface  of  the  plate  to  assure  himself  positively  that 
the  water  is  in  motion  all  over  the  surface,  otherwise  the  washing 
will  not  be  well  done.  The  above  dimensions  will  answer  for 
all  sizes  of  plates  up  to  8  x  10  and  even  10  x  12. 

Ten  to  fifteen  minutes  is  the  right  time  for  washing  a  negative, 
although  much  less  is  often  given  by  hasty  operators.  It  is 
almost  as  important  to  wash  the  bach  as  the  face,  although  the 
latter  requires  only  simple  rinsing  off.  If  this  be  neglected,  por¬ 
tions  of  the  hyposulphite  bath  will  remain  there,  and,  when  the 
plate  is  set  up  to  dry,  will  run  down  to  the  edge,  and  thence  be 
drawn  up  by  capillary  attraction  into  the  film,  preparing  the  way 
for  spots  and  stains  at  some  future  time. 

The  plates  are  next  allowed  to  dry,  either  reared  up  corner- 
wise  in  a  drying-frame,  or  simply  supported  in  a  vertical  posi¬ 
tion,  resting  on  several  thicknesses  of  blotting-paper.  Fig.  10 
represents  a  very  convenient  rack  made  by  simply  attaching 
upright  pieces  to  a  flat  board.  Racks  can  be  purchased  of  the 
dealers  to  hold  a  much  larger  number  of  negatives ;  the  form  in 
the  figure  is,  however,  very  convenient,  and  safer. 

From  the  time  that  the  plate  enters  the  fixing-bath  the  plate 
may  be  exposed  to  the  light  without  injury. 

If  it  is  intended  to  redevelop  the  plate  after  instead  of  before 


MAKING  THE  NEGATIVE. 


37 


Fig.  10. 


fixing,  the  washing  mast  be  equally  careful  after  the  fixing  solu¬ 
tion  is  applied,  or  the  application  of  the  redeveloping  solution 
will  cause  brown  stains. 

Sore  hands  produced  by  contact  with  chemicals  sometimes  give 
a  good  deal  of  trouble.  Where  a  tendency  of  the  sort  exists,  the 
photographer  should  endeavor  to  keep  his  hands  as  much  as  pos¬ 
sible  out  of  contact  with  chemical  solution,  and  should  thoroughly 
wash  them  immediately  after  any  such  contact.  At  the  close  of 
the  day’s  work  the  hands  should  be  well  scrubbed  with  soap  and 
a  nail  brush,  and  then  be  moistened  with  cologne-water  to  which 
one-eighth  of  its  bulk  of  glycerine  has  been  added.  This  will 
strengthen  the  skin,  and  at  the  same  time  retain  its  softness  and 
pliability.  Carbolic  acid,  five  drops  to  the  ounce  of  water,  has 
been  found  useful. 


§  11. — Varnishing  the  Negative. 

To  varnish  a  negative  well  will  require  both  care  and  attention 
on  the  part  of  the  beginner,  until  by  habit  and  practice  a  com¬ 
plete  control  over  the  operation  is  obtained. 

Choice  of  Varnish. — First  as  to  the  selection  of  varnish.  The 
beginner  should  never  attempt  to  make  his  own,  but  always  pro¬ 
cure  a  reliable  commercial  varnish.  The  experienced  photogra¬ 
pher  should  always  make,  never  buy ;  not  so  much  for  economy, 
though  the  saving  is  material,  but  in  order  to  be  certain  that  he 
has  exactly  what  he  wants — a  hard,  tough  varnish,  made  out  of 
the  very  best  materials.  Suitable  directions  will  be  found  in  the 
latter  part  of  this  manual  for  preparing  negative  varnishes* 

The  commercial  varnishes  may  be  divided  into  two  classes — the 


38 


INTRODUCTION  TO  PHOTOGRAPHY. 


benzine  and  the  spirit  varnishes.  The  former  will  sometimes 
dry  clear,  even  if  used  cold;  the  latter  always  require  the  aid  of 
heat.  On  the  other  hand,  the  benzine  varnishes  (so  far  as  the 
writer’s  experience  goes)  always  reduce  the  strength  of  the  nega¬ 
tive  considerably,  whilst  the  spirit  varnishes  do  not;  and  the 
latter  are  every  way  more  reliable.  Either  sort  that  the  ope¬ 
rator  becomes  accustomed  to  he  will  consider  the  more  easy, 
and  it  is  best  to  adopt  some  particular  varnish,  and  use  it  always. 
The  writer  prefers  the  spirit  varnishes.  The  two  different  sorts 
can  always  be  distinguished  by  the  odor. 

Applying  the  Varnish. — First  dust  off*  the  plate,  either  ver.y  gently 
with  a  very  soft,  broad  camel’s-hair  brush,  or  by  blowing  with  a 
bellows.  With  plates  developed  with  iron,  or  redeveloped,  the 
latter  is  the  better  plan.  To  apply  a  spirit  varnish,  warm  the 
plate  gently  ;  in  winter  a  coal  stove  will  be  convenient,  in  summer 
a  gas  stove  is  most  commonly  employed.  Try  the  temperature 
by  holding  it  at  one  corner  with  the  left  hand,  and  moving  the 
right  hand  under  it  and  applying  the  side  of  the  hand  and  back 
of  thumb  to  various  places  to  see  if  the  heat  be  uniform.  To  be 
right,  the  temperature  should  be  quite  warm,  but  not  in  the  least 
hot;  there  should  be  a  distinct,  pleasant  sensation  of  warmth,  but 
no  more.  If  too  hot,  set  aside  a  few  minutes  to  cool.  If  used 
too  hot,  there  is  danger  of  getting  lines,  as  will  be  presently  de¬ 
scribed.  If  used  too  cool,  the  varnish  will  probably  “  dry  dead.” 
A  benzine  varnish  requires  rather  less  heat  than  a  spirit  varnish. 
Some  use  it  cold  when  the  weather  is  clear  and  dry.  The  writer 
prefers  to  use  heat  with  all  varnishes.  Taking  a  convenient  posi¬ 
tion  in  front  of  a  window  so  as  to  watch  by  the  reflection  all  the 
movements  of  the  varnish,  pour  it  on  precisely  in  the  same  way 
as  with  collodion.  Having  put  on  a  liberal  supply,  slant  the  plate 
towards  you  and  bring  the  pool  of  varnish  towards  you,  in  a  full , 
slow  v:ave ,  keep  its  border  as  square  as  possible,  making  it  advance 
slowly  and  quietly ;  if  one  edge  gets  a  little  the  advance,  incline 
the  plate  the  other  way  to  bring  it  up.  With  too  little  varnish 
or  too  much  tilt  to  the  plate,  long  arms  will  start  out,  and  whilst 
you  are  slanting  the  plate  this  way  and  that  to  get  it  covered  on 
some  part  of  the  border,  the  wave  will  stop  moving,  and  a  line 
may  result. 

Having  now  got  the  whole  plate  covered,  keep  it  quite  level 
or  even  tilt  it  backward,  so  as  to  send  a  returning  wave  clear  up 
to  the  far  end  of  the  plate.  The  varnish  should  rest  on  the  whole 


MAKING  THE  NEGATIVE, 


39 


plate  some  seconds  before  beginning  to  pour  off,  otherwise  it  will 
not  soak  in  sufficiently,  and  so  dry  dead. 

The  length  of  time  necessary  for  the  varnish  to  rest  on  the  plate 
varies  a  good  deal.  The  more  a  plate  has  been  redeveloped  the 
longer  it  will  need  the  varnish  to  remain  upon  it ;  the  thicker 
the  varnish,  the  less  time  is  required.  A  thick  varnish  with  a 
close  film  will  need  only  seven  to  ten  seconds.  A  very  thin  var¬ 
nish  with  a  spongy  film  may  need  fifteen  to  twenty.  Generally 
speaking,  eight  or  ten  seconds  will  be  a  proper  time ;  a  few 
trials  on  rejected  negatives  will  show  what  is  needed.  The  time 
here  spoken  of  is  to  elapse  after  the  negative  has  been  completely 
covered. 

Having  let  it  soak  in  sufficiently,  incline  it  very  little ,  so  that  it 
will  run  off  at  the  right-hand  near  corner  into  the  11  pouring  off 
bottle”  held  there  to  receive  it.  After  it  has  run  slowly  for  a 
couple  of  seconds,  the  plate  being  of  course  nearly  level,  bring  it 
suddenly  ujp  by  a  quick  movement  till  it  is  vertical ,  and  there  hold  it 
for  haif  a  minute  or  more  that  it  may  drain  and  set.  Rock  it 
from  right  to  left  precisely  as  in  the  case  of  a  collodion  plate. 
Let  it  drain  until  it  almost  ceases  to  drop,  and  then  hold  it  pretty 
close  to  a  hot  stove  until  perfectly  hard,  but  not  longer  than 
necessary  for  this.  The  heat  of  the  stove  should  be  about  as 
great  as  the  hand  can  bear  in  holding  the  plate. 

The  varnish  must  of  course  not  be  returned  into  the  same  bottle 
as  that  from  which  it  was  poured  off,  otherwise  it  will  soon  have 
bits  of  collodion,  dust,  etc.,  on  it.  The  writer  invariably  manages 
as  follows :  Take  twro  clean  six-ounce  vials,  fill  one  with  filtered 
varnish,  put  on  the  neck  of  the  other  a  funnel  of  about  two  and 
one-half  inches  in  diameter,  with  a  paper  filter  in  it.  Pour  off* 
from  the  plate  into  this  filter ;  in  this  way  there  will  be  less 
varnish  lost,  and  less  trouble  in  getting  the  stream  from  the  plate 
into  the  bottle.  The  varnish  having  run  through  the  filter,  is  of 
course  clean,  and  when  the  first  bottle  is  empty,  the  funnel  is 
transferred  to  it,  and  the  operation  reversed.  The  funnel  with 
the  filter  in  it  may  stand  permanently  in  the  neck  of  the  bottle, 
to  which  it  supplies  the  place  of  a  cork,  and  so  is  always  ready. 

The  varnish  which  has  been  poured  off  from  plates  has  of 
course  lost  alcohol  by  evaporation,  and  is  thicker  than  at  first. 
Therefore  before  the  pouring-off  bottle  is  used  for  varnishing 
with,  a  little  alcohol  must  be  added — one-sixth  or  one-eighth  its 
bulk,  in  round  numbers,  but  this  is  a  point  of  which  the  operator 


40 


INTRODUCTION  TO  PHOTOGRAPHY. 


must  learn  as  quickly  as  possible  to  judge  for  "himself.  If  varnish 
is  too  thin  it  is  apt  to  dry  dead,  and  does  not  properly  protect  the 
plate.  A  negative  film  varnished  with  a  very  thin  varnish  can 
be  easily  rubbed  up  by  the  finger.  Such  negatives  are  of  course 
very  perishable,  and  are  soon  destroyed  in  printing.  If  too  thick 
it  is  less  easy  to  work  with,  and  removes  the  film  too  far  from 
the  paper  in  printing,  thus  (especially  in  shade-printing)  diminish¬ 
ing  the  sharpness  of  the  print. 

Some  varnishes  require  heat  only  before  their  application; 
generally,  however,  they  should  be  dried  by  heat,  as  well  as  be 
applied  on  a  warm  plate.  The  drying  by  heat  expels  the  vola¬ 
tile  portions  more  thoroughly,  and  renders  the  varnish  less  liable 
to  become  soft  and  sticky  in  printing. 

The  main  points  are  to  get  the  corners  covered  immediately 
after  you  begin  to  pour,  to  put  on  enough,  and  to  bring  it  down  as 
above  explained  to  a  full,  slow ,  square  wave.  The  learner  cannot 
pay  too  close  an  attention  to  these  directions.  By  doing  so  he 
will  get  a  smooth,  even  plate.  Neglecting  them,  he  will  find:— 

Ridges. — These  start  from  some  point  at  the  edge  of  the  plate 
and  extend  some  distance  over  the  face  of,  or  even  all  across  the 
negative.  If  strong  enough  to  be  likely  to  show  in  the  printing, 
the  plate  must  be  flowed  with  alcohol,  drained,  and  revarnished. 

Lines  result  from  a  momentary  stopping  of  the  wave  of  var¬ 
nish.  The  varnish  dries  a  little  on  the  hot  plate  during  the 
pause,  and  the  result  is  a  line  exactly  marking  the  position  it 
then  had.  The  hotter  the  plate,  the  more  apt  lines  will  be  to 
appear.  If  a  line  has  been  made  and  is  seen  before  you  begin  to 
pour  off,  it  may  be  lessened,  and  sometimes  entirely  removed,  by 
keeping  on  the  varnish  a  few  seconds  longer  than  usual  before 
beginning  to  pour  off.  Fine  parallel  lines  may  come  from  omitting 
to  rock  the  plate. 

Drying  Dead. — This  results  in  the  production  of  a  film  looking 
like  ground  glass — -sometimes  fine,  sometimes  coarse.  If  fine,  it 
may  not  show  at  all  in  the  printing ;  if  coarse,  it  will.  This  may 
arise  from  several  sources  : — 

From  Dampness  of  the  Film. — After  the  film  is  surface  dry,  it 
takes  a  long  time  to  dry  through,  and  the  drying  must  be  thorough 
before  the  varnish  is  applied.  So,  too,  the  film  is  very  absorbent 
of  atmospheric  moisture,  and  even  after  thorough  drying  and 
standing  for  weeks,  may  easily  in  damp  weather  absorb  enough  to 


MAKING  THE  NEGATIVE. 


41 


affect  the  varnishing.  It  is  therefore  better,  so  far  as  convenient, 
to  varnish  in  clear  dry  weather,  or  at  least  after  the  plate  has 
remained  some  time  in  a  warm  dry  room. 

Too  thin  a  varnish  may  also  cause  drying  dead,  or  too  little  ap¬ 
plied.  If,  as  soon  as  the  plate  is  covered,  the  varnish  be  poured 
off  again,  it  will  almost  certainly  dry  dead,  because  the  surface 
only  was  moistened ;  this  presently  soaks  in  and  leaves  the  film 
only  half  saturated  with  varnish.  This  is  perhaps  the  commonest 
of  all  causes  of  drying  dead,  and  often  (by  the  beginner)  the  last 
suspected.  Therefore  the  writer  advises,  if  the  operator  is 
troubled  by  this  difficulty,  to  proceed  as  follows :  Put  on  an 
abundant  supply  of  varnish  after  covering  the  plate,  send  back  a 
wave  to  the  far  end,  and  then  hold  the  plate  quite  level  and 
motionless  for  at  least  twelve  seconds  quietly  counted.  At  the 
end  of  this  time,  incline  the  near  right-hand  corner  until  a  steady 
stream  runs  into  the  bottle,  and  then,  as  before  directed,  bring 
the  end  up  with  a  quick  motion. 

Negatives  will  be  found  to  vary;  some  will  dry  smooth  with  the 
very  same  treatment  that  gives,  perhaps  with  the  very  next  one 
varnished,  a  dead  film.  This  depends  upon  the  amount  of  re¬ 
development  they  have  received ;  the  more  redeveloped,  the  more 
apt  to  dry  dead,  because  there  is  more  silver  powder  to  soak  in 
the  varnish.  If  found  necessary,  the  varnish  may  be  kept  on 
even  for  fifteen  or  twenty  seconds,  to  penetrate  thoroughly. 

Special  care  should  always  be  taken  not  to  allow  the  varnish 
to  get  over  the  edges  upon  the  back  of  the  plate,  not  only 
because  it  is  troublesome  to  clean  it  off,  but  because  if  a  stream 
of  varnish  runs  across  the  back  of  the  plate,  it  will  often  happen 
that  the  corresponding  part  of  the  face  will  dry  dead,  the  evapo¬ 
ration  going  on  at  the  back  keeps  the  corresponding  portion  of 
the  face  cool,  and  thus  prevents  the  drying  smooth. 

Breathing  on  the  plate  may  at  times,  and  under  some  circum¬ 
stances,  lead  to  spots  of  deadness. 

Often  a  deadness  of  the  surface  will  not  affect  the  printing. 
An  experienced  operator  will  be  able  to  distinguish  at  once 
whether  the  evil  is  great  enough  to  bring  about  this  result.  If, 
when  the  plate  is  examined  by  allowing  the  light  to  fall  through 
it,  the  deadness  is  not  at  all  or  very  slightly  perceptible,  the  nega¬ 
tive  will  probably  print  well. 

Revarnishing. — But  if  the  roughness  is  quite  distinct,  a  remedy 
must  be  applied.  Since  the  first  edition  of  this  work  was  printed, 
4 


42 


INTRODUCTION  TO  PHOTOGRAPHY. 


it  occurred  to  the  writer  to  remove  the  varnish  at  once  by  hot 
alcohol,  and  this  proves  to  be  much  the  best  method. 

The  defective  plate  is  to  be  warmed  precisely  as  for  varnishing, 
and  then  instead  of  varnish,  an  abundant  quantity  of  ninety-five 
per  cent,  alcohol  is  poured  on  and  well  worked  over  the  plate ;  this 
is  then  poured  off  and  a  second  portion  used  to  wash  off  residue. 
The  plate  is  then  allowed  a  few  moments  to  become  quite  dry,  is 
heated  again,  and  varnished  precisely  as  with  a  new  plate.  This 
operation,  when  carefully  performed,  leaves  nothing  to  be  de¬ 
sired  in  its  results. 

Ridges ,  that  is,  lines  of  greater  thickness  extending  across  the 
plate,  may  be  easily  got  rid  of  in  the  same  way. 

When  it  is  intended  to  print  a  very  large  number  of  positives 
from  one  negative,  two  coats  of  varnish  may  be  applied.  Mr.  Gr. 
W.  Wilson  always  gives  two  coats,  touching  out  defects  between 
the  two.  In  this  case,  the  varnish  should  be  thinner  than  when 
one  coat  only  is  applied. 

It  is  a  good  plan,  as  soon  as  the  face  of  the  varnished  plate  is 
dry,  to  draw  a  piece  of  blotting-paper  along  the  lower  edge  of  the 
glass ;  this  prevents  the  production  of  a  thick  ridge  there,  which 
would  have  a  tendency  to  lift  up  the  paper  in  printing,  and  pre¬ 
vent  a  close  contact  with  the  adjoining  parts. 


§  12. — Ambrotypes  and  Ferrotypes. 

If  the  development  of  a  negative  be  stopped  as  soon  as  all  the 
details  are  out  and  considerably  before  printing  density  is  reached, 
we  have  a  picture  called  an  Ambrotype  when  made  on  glass,  and 
a  Ferrotype  when  made  on  a  thin  plate  of  varnished  iron.  The 
high  lights  appear  white  by  reflected  light,  because  of  the  white¬ 
ness  of  the  silver  deposit  of  which  they  are  made;  the  transparent 
portions  are  rendered  black  by  black  varnish  applied  on  the  back, 
in  the  case  of  the  ambrotype,  and  by  the  black  face  of  the  metal 
in  the  case  of  the  ferrotype. 

All  negatives,  therefore,  in  an  early  stage  of  their  develop¬ 
ment,  are  ambrotypes.  But  to  get  the  best  effects,  it  is  found  ad¬ 
vantageous  to  use  in  the  negative  bath  a  little  more  acid,  and  to 
employ  an  old  and  ripe  collodion,  for  it  is  necessary  to  keep  the 
shadows  perfectly  transparent  and  free  from  the  least  tendency  to 
veil,  which  would  destroy  their  depth  and  richness. 

An  ordinary  negative  collodion  may  be  used  if  it  is  thoroughly 


MAKING  THE  NEGATIVE. 


43 


ripe  ;  if  not,  tincture  of  iodine  may  be  added  till  it  is  sherry  wine 
colored.  (Tincture  of  iodine  may  be  purchased,  or  may  be  made 
by  dissolving  iodine  in  alcohol.  Thirty  grains  of  iodine  to  the 
ounce  of  alcohol  is  a  convenient  strength.) 

Some  photographers  prefer  a  special  collodion  containing  iodide 
of  potassium,  now  rarely  used  in  negative  collodions.  Mr.  Thomas, 
of  New  York,  uses  the  following  proportions: — 

Iodide  of  potassium . 50  grains. 

Bromide  of  potassium . 30  “ 

Dissolve  these  salts,  with  the  aid  of  heat,  in  3  ounces  of  alcohol, 
Take  60  grains  of  pyroxyline,  dissolve  it  in  5  ounces  of  ether  and 
2  of  alcohol.  Then  add  the  above  while  still  hot. 

The  developer  is  to  be  the  same  as  for  negatives,  taking  care 
that  it  be  sufficiently  acidified,  for  which  purpose  one-half  more 
acetic  acid  may  be  added  than  for  negatives. 

§  13. — General  Remarks. 

Avoid  doing  anything  which  may  cause  dust  in  the  dark  room. 
Keep  the  dark  slide  clean  and  well  wiped. 

Notice  the  camera  from  time  to  time  to  assure  yourself  that  the 
wood  work  is  close  and  tight. 

See  that  the  focussing  slide  sits  tight  and  close  up.  The  spring 
that  holds  it  to  the  body  of  the  camera  will  sometimes  get  out  of 
order  and  affect  the  two  slides  differently,  so  that  one  comes  up 
more  closely  than  the  other.  The  result  of  this  ^ill  be  that  the 
focussing  surface  no  longer  corresponds  with  the  sensitive  film, 
and  no  matter  how  carefully  the  focussing  be  done,  the  pictures 
will  not  be  accurately  sharp. 

Make  sure  that  the  camera-stand  is  absolutely  steady  and  not 
given  to  trembling. 

See  that  the  dark  room  is  thoroughly  ventilated,  so  that  whilst 
at  work  you  are  not  inhaling  noxious  vapors,  and  as  little  as 
possible  of  the  fumes  of  collodion. 

Removing  stains  from  hands. — Fresh  stains  come  away  much  more 
easily  than  those  that  have  been  exposed  to  light.  Dilute  hydro¬ 
chloric  acid,  to  which  a  little  solution  of  bichromate  of  potash  is 
added,  is  very  effectual.  It  should  be  followed  by  an  applica¬ 
tion  of  a  vegetable  acid,  tartaric,  citric,  or  better  yet,  binoxalate 
of  potash,  which  last  is  also  convenient  for  removing  ink  stains. 
One  or  more  of  these  substances  should  be  kept  at  hand  in  solu- 


44 


INTRODUCTION  TO  PHOTOGRAPHY. 


tion  to  use  after  the  bichromate  solution,  which  otherwise  leaves 
behind  a  yellow  stain  and  disagreeable  odor;  the  injurious  effect 
upon  the  skin  is  also  diminished.  Perchloride  of  iron,  which  has 
been  recommended,  the  writer  has  not  found  to  answer.  Cyanide 
of  potassium  should  not  be  used.  Silver  stains  on  clothes  are  best 
removed  by  solution  of  corrosive  sublimate,  which  destroys  them 
effectually  and  without  injuring  either  the  texture  or  the  color. 


CHAPTER  TIL 

PRINTING. 

§  1. — Sensitizing. 

As  albumenized paper  is  now  almost  exclusively  used  in  positive 
printing,  it  will  be  the  only  method  described  in  this  introduction  ; 
others  will  be  hereafter  given. 

Those  who  operate  upon  a  large  scale  sensitize  their  sheets 
whole,  others  divide  them  into  halves  or  quarters,  and  one  corner 

is  to  be  folded  backwards  for 
half  an  inch  or  three-quarters. 
The  piece  is  then  held  at  its 
two  ends,  is  folded  into  a  loop 
by  bringing  the  hands  some¬ 
what  together  so  that  the  cen¬ 
tre  will  be  lowest,  and  the 
albumenized  surface  under¬ 
most.  The  centre  of  the  sheet 
is  made  to  touch  the  bath  first, 
and  then,  by  opening  the  hands 
and  lowering  them,  the  whole 
surface  is  regularly  opened  out  on  the  bath.  In  this  way  air- 
bubbles  are  avoided.  Should  an  air-bubble  remain  under  the 
paper,  its  place  will  be  marked  by  a  white  spot  in  the  print. 

Positive  Bath. 

Water . 22  ounces. 

Nitrate  of  silver . 3  “ 

The  paper  remains  on  it  about  four  minutes  in  winter,  and  two 
in  summer.  It  is  then  lifted  off  by  the  corner  turned  up,  and 


Fig.  11. 


Laying  the  sheet  on  the  printing  bath. 


PRINTING. 


45 


pinned  to  a  rod  or  string  to  dry.  A  convenient  method  is  to  take 
a  long  strip  of  wood,  and  glue  on  it  at  spaces  corks,  into  which 
to  stick  the  pins. 

When  the  bath  turns  dark,  shake  it  up  with  half  an  ounce  of 
kaolin.  Let  it  stand  some  hours,  with  occasional  shaking,  and 
filter. 

Examine  the  bath  from  time  to  time  with  red  and  blue  litmus 
paper,  and  keep  it  as  nearly  neutral  as  possible.  If  the  blue 
litmus  turns  red,  the  bath  is  too  acid,  and  may  be  neutralized 
with  a  grain  or  two  of  bicarbonate  of  sodium.  If  red  litmus 
paper  turns  blue,  the  bath  is  alkaline,  and  a  little  dilute  nitric 
acid  must  be  carefully  added.  It  is  best  to  have  the  solution  an 
inch  deep  in  the  glass  or  porcelain  bath.  Too  shallow  a  bath 
tends  to  irregular  action. 

See  that  the  paper  is  thoroughly  dry  before  printing  it.  A 
dense  negative  prints  best  in  the  sun,  a  thin  one  in  the  shade. 
That  is,  it  is  to  be  exposed  at  a  window  to  a  good  light,  but  not 
to  sunshine.  A  negative  too  thin  to  give  a  good  result  in  any 
other  way,  may  often  be  successfully  printed  by  laying  a  sheet 
of  tissue  paper  over  it. 

Printing  frames  are  made  in  many  different  patterns.  The 
writer  recommends  the  bar  frame  (Fig.  12)  to  the  exclusion  of  all 
so-called  improvements  on  it,  which 
generally  fail  to  bring  the  paper 
closely  up  to  the  negative,  unles  the 
pressure  is  dangerously  increased. 

The  padding  behind  the  paper  should 
be  of  soft  woollen  material,  felt,  or 
best  of  all,  piano-cloth. 

Print  till  the  highest  lights  just 
begin  to  color.  By  this  time  the 
dark  shadows  ought  to  show  the 
greenish,  almost  metallic,  look 
known  as  “  bronzing.” 

Examine  the  print  from  time  to 
time,  taking  the  frame  to  a  darker 
part  of  the  room,  open  the  back 
gently,  taking  care  not  to  shift  the  print,  bend  it  back,  and  judge 
of  the  degree  to  which  the  printing  has  gone. 

As  fast  as  the  exposure  is  finished,  throw  the  prints  into  a  dark 
drawer. 


Fig.  12. 


46 


INTRODUCTION  TO  PHOTOGRAPHY. 


When  all  are  ready,  proceed  to  wash  them  by  putting  them 
one  by  one  into  a  basin  of  water,  where  they  lie  ten  minutes. 
This  water  is  to  be  carefully  added  to  the  residues,  as  it  is  rich 
in  silver.  Change  the  water  two  or  three  times,  then  tone. 

As  the  printiug-bath  will  continually  lose  in  strength,  it  should 
be  kept  up  by  adding  crystals  of  nitrate  of  silver,  remembering 
that  each  sheet  of  18  x  22  will  remove  about  a  drachm  and  a 
quarter  of  nitrate  of  silver. 

§  2.— Toning  Bath. 


Water . 16  ounces. 

Chloride  of  gold . 4  grains. 

Acetate  of  sodium . 1  ounce. 


If  mixed  with  warm  water,  it  will  in  two  or  three  hours  be 
ready  for  use,  otherwise  it  is  best  kept  till  next  day.  In  very 
cold  weather,  a  little  more  gold  must  be  used;  and  the  bath, 
except  in  hot  weather,  should  be  warmed  till  it  is  tepid. 

Put  in  only  a  few  prints  at  a  time,  and  keep  them  constantly 
moving  about.  When  they  reach  the  shade  desired,  let  them 
remain  a  little  longer,  as  they  will  afterwards  recede  a  little  in 
color;  then  take  them  out,  pass  them  through  clean  water,  and 
proceed  to  fixing.  This  bath  will  give  rich  warm  tones,  but  not 
black  ones,  for  which,  if  desired,  the  carbonate  bath,  or  better, 
the  chloride  of  lime  bath  (see  beyond),  must  be  used. 

Prints  that  look  blue  when  finished,  have  been  over-toned  by  too 

long  an  immersion. 

{ 

§  3. — Fixing  Bath. 

Water  . . 32  ounces. 

Hyposulphite  of  sodium . 4  “ 

Keep  the  prints  moving  about  in  this,  and  leave  them  in  fifteen 
minutes.  The  above  bath  will  suffice  for  two  whole  sheets,  and 
must  be  increased  in  proportion  if  more  are  to  be  toned.  Never 
use  on  any  subsequent  day  a  bath  that  has  had  even  only  one  single 
print  fixed  in  it ,  or  the  print  so  toned  will  surely  fade  in  time. 

§  4. — Washing. 

A  very  thorough  washing  is  needed  to  prevent  fading.  Prints 
thrown  into  a  tank  into  which  a  tolerable  stream  of  moving  water 
falls,  will  be  sufficiently  washed  in  six  to  ten  hours,  provided 
there  are  not  too  many  of  them.  When  the  number  is  large,  the 
tank  must  be  continually  emptied  of  water  and  refilled. 


A  FEW  GENERAL  RULES  FOR  BEGINNERS. 


47 


CHAPTEK  I Y. 

A  FEW  GENERAL  RULES  FOR  BEGINNERS.1 

1.  Invariably  wash  the  fingers  under  the  tap  immediately 
after  they  have  been  in  any  solution,  but  most  particularly  after 
hyposulphite.  Neglect  of  this  will  transfer  portions  of  one  solu¬ 
tion  to  another,  and  lay  the  foundation  for  long  series  of  failures, 
which  may  prove  utterly  distressing  and  perplexing. 

2.  Do  not  be  actuated  by  an  ambition  to  commence  with  diffi¬ 
cult  work.  Point  the  camera  out  of  the  window,  and  take  the 
view,  such  as  it  is,  until  it  is  done  with  certainty  and  success. 
After  that  will  be  time  enough  to  try  portraiture — last  of  all, 
copying. 

3.  Begin  with  small  plates,  and  do  not  try  large  ones  until 
the  smaller  are  mastered.  Half-size  will  be  the  largest  proper  to 
begin  with. 

4.  Do  not  undertake  to  make  collodion  before  its  use  is  learned. 
Be  satisfied  to  purchase  that  which  some  experienced  friend  re¬ 
commends. 

5.  Do  not  tend  towards  intensifying  thin  pictures  by  after-treat¬ 
ments.  When  photography  was  less  understood  this  was  oftener 
necessary.  It  is  better  to  wash  off  and  begin  again,  and  generally 
less  trouble  to  get  a  better  result. 

6.  The  quickest  way  to  learn  is  this :  take  any  simple  object 
as  above,  a  brick  house,  for  example,  and  try  it  again  and  again, 
varying  the  length  of  exposure  and  the  length  of  development, 
until  a  negative  is  got  that  prints  exactly  right.  This  will  teach 
more  in  a  few  mornings  than  as  many  weeks  of  random  work. 

7.  Successes  that  come  by  chance  are  worthless,  and  prove 
nothing  as  to  ability.  Try  to  know  exactly  the  causes  of  success 
and  of  failure. 

8.  The  right  exposure  may  often  be  got  the  first  time,  but  not 

1  At  the  end  of  this  volume  will  be  found  descriptions  of  those  simple  chemical 
manipulations  which  are  used  in  photography,  and  with  which  the  beginner 
will  do  well  to  make  himself  early  familiar. 


48 


INTRODUCTION  TO  PHOTOGRAPHY. 


certainly ;  yet  a  careful  examination  of  the  first  trial  ought  to 
enable  one  to  make  sure  of  the  second. 

9.  If  the  camera  needs  to  be  placed  in  the  sunshine,  throw  the 
focussing  cloth  over  it  before  the  shutter  is  drawn  out  to  make 
the  exposure.  The  direct  light  of  the  sun  may  find  its  way 
through  cracks  too  small  to  admit  diffused  light. 

10.  Once  in  a  while  wipe  out  the  camera  with  a  damp  cloth  to 
remove  dust,  which  by  settling  on  the  plate  may  cause  pin-holes 
or  comets. 

11.  Treat  the  lenses  with  the  utmost  care.  Never  leave  them 
about ;  never  wipe  them  with  anything  but  the  softest  old  linen 
cambric,  perfectly  clean,  and  not  even  so  except  when  needed. 

12.  Do  not  unscrew  the  tubes  unnecessarily  to  wipe  the  inside 
surfaces  of  the  lenses,  or  for  any  other  purpose,  and  always  do 
this  in  dry  weather,  or  damp  air  will  be  admitted,  which  will  be 
apt  later  to  leave  a  dew  on  the  lenses.  If  any  of  the  lenses  are 
set  loosely  in  the  tube,  be  sure  they  are  replaced  with  the  same 
side  front  as  before. 

18.  Do  not  let  either  the  lenses  or  the  camera  stand  in  the  sun, 
the  result  will  be  warping  and  splitting  of  the  wood,  and  discolo¬ 
ration  of  the  lens. 

14.  Be  sure  that  the  camera  stand  is  free  from  vibration.  Un¬ 
cover  the  lens  very  gently  so  as  not  to  shake  the  camera  in  the 
least,  or  the  definition  will  be  impaired. 

15.  Unless  the  ground  glass  is  of  the  best,  the  focus  cannot  be 
taken  with  accuracy.  Much  of  the  ground  glass  in  cameras  made 
for  sale  is  very  poor.  The  glass  should,  in  fact,  not  be  ground  at 
all,  but  only  “grayed,”  that  is,  have  its  surface  removed  by 
rubbing  with  fine  emery  powder.  Focus  a  brick  house  200  feet 
off  with  a  short  focus  lens,  and  if  the  white  lines  of  the  mortar 
cannot  be  seen,  either  with  the  naked  eye  or  with  a  magnifier, 
the  glass  is  too  coarsely  ground ;  and  it  is  to  be  expected  that  all 
the  work  done  with  it  will  be  inferior. 

16.  Focussing  with  a  microscope  is  less  trying  to  the  eyes,  and 
gives  sharper  work.  The  larger  the  lens  of  the  microscope  used, 
the  less  the  eye  is  strained.  An  engraver’s  glass  set  in  horn 
is  good,  but  a  similar  one,  an  inch  and  a  half  or  two  inches  in 
diameter,  tires  the  eye  still  less. 

17.  Learn  exactly  how  to  make  a  negative  bath,  and  then  avoid 
doctoring.  For  the  most  part  it  will  only  be  injured.  Add  a 
very  little  carbonate  of  soda,  and  sun  it,  if  out  of  order,  for  some 


A  FEW  GENERAL  RULES  FOR  BEGINNERS. 


49 


hours  in  direct  sunlight,  then  filter  and  acidulate  as  directed  for 
a  new  bath.  Filter  first,  then  acidulate. 

18.  Decaying  organic  matter,  foul  smells,  sulphuretted  hydro¬ 
gen,  and  fumes  of  ammonia  may  be  expected  to  produce  fog. 

19.  Do  not  think  it  necessary  to  have  the  dark  room  too  dark. 
There  may  be  light  enough  to  work  with  perfect  comfort,  and 
the  strain  on  the  eyes  in  going  backwards  and  forwards  will  be 
so  much  the  less :  an  important  consideration. 

20.  Have  nothing  to  do  with  cyanide  of  potassium.  It  is  a 
substance  of  which  the  photographer  has  no  real  need.  If  used  at 
all,  it  should  be  left  to  those  who  have  learned  their  experience 
on  less  dangerous  materials. 

21.  Remember  that  most  chemicals  are  poisons,  and  that  if  the 
fingers  are  not  washed  immediately  after  being  plunged  in  them, 
or  if,  even  with  this  precaution,  they  are  kept  long  in  the  solu¬ 
tions,  mischief  may  ensue.  What  this  mischief  may  be  is  of  so 
gradual  and  insidious  a  nature,  as  to  be  ascribed  to  any  other 
cause  than  the  right  one. 

22.  Remember  also  that  most  fumes  are  injurious.  Yapors  of 
ammonia  disorganize  and  paralyze  the  blood  corpuscles.  Yapor 
of  ether  is  very  injurious  to  the  nervous  system,  produces  head¬ 
ache,  and  depresses  the  whole  tone  of  the  body.  Nitric  acid  is 
highly  poisonous  ;  its  fames,  when  inhaled  for  a  sufficient  length 
of  time,  will  cause  death. 

28.  Therefore  make  every  provision  for  thorough  and  complete 
ventilation.  And  do  not  fancy  (as  many  most  unwisely  do)  that 
because  the  senses  become  habituated  to  such  fumes,  and  cease 
to  be  inconvenienced  by  them,  that  the  system  is  therefore  not 
suffering. 

24.  Adopt  invariably  the  maxim,  that  whatever  is  worth  doing 
is  worth  doing  well.  Practice  never  makes  perfect  without  care, 
and  thoughtful  and  intelligent  observation.  Some  will  do  a  thing 
all  their  lives,  and  always  badly. 

25.  Acquire  the  habit  of  rinsing  out  all  the  vessels  as  soon  as 
emptied,  and  of  not  leaving  the  adhering  portions  to  dry  on  the 
bottom  and  sides,  when  it  will  take  five  times  the  trouble  to  get 
it  out. 

26.  Make  it  a  rule  to  wash  every  vessel  before  you  put  it  away, 
and  again  before  using  it.  Never  trust  to  anything  being  clean, 
but  make  it  so.  If  there  is  any  one  thing  that  is  essential  in 
photography,  it  is  care  of  this  sort.  The  delicate  reactions  on 


50 


INTRODUCTION  TO  PHOTOGRAPHY. 


which  photographic  processes  depend  are  sufficiently  exacting, 
without  further  embarrassing  the  processes  by  introducing  foreign 
matter  of  unknown  nature. 

27.  Never  forget  that  no  vessel  is  rendered  clean  (even  if  what 
it  has  contained  has  been  merely  an  aqueous  solution)  by  simply 
pouring  water  in  and  throwing  it  out. 

Hold  therefore  the  vessel,  whether  beaker,  bowl,  bottle,  or 
whatever  it  may  be,  under  the  tap,  so  that  the  water  may  run 
over  every  part,  inside  and  out.  Outside,  because  it  is  never 
certain  that  a  glass  vessel  is  clean  inside  unless  it  has  also  been 
made  so  outside.  Remember  that  if  a  vessel  be  hastily  rinsed 
out,  there  may  be  left  drops  of  the  old  solution  adhering  to  the 
sides  above  the  part  washed,  and  that  a  single  drop  so  left  may 
spoil  the  following  operation.  This  direction  may  be  thought  so 
much  a  matter  of  course  as  to  be  superfluous;  it  is  not  so. 

In  all  cases,  except  where  the  old  contents  are  very  easily 
removable  by  water,  employ  the  bichromate  cleaning  solution, 
which  for  this  purpose  may  be  made  of  double  or  treble  strength, 
so  as  to  work  more  energetically. 

28.  In  the  field,  before  making  the  first  exposure,  take  pains 
to  make  sure  that  everything  is  right.  (See  especially  sections  3 
and  4  in  chapter  on  Landscape  Photography.) 

29.  Make  it  a  fixed  rule  that  every  failure  shall  be  made  the 
stepping-stone  to  some  new  advance.  If  by  accident  any  work  is 
destroyed  or  injured,  make  it  a  rule  that  it  shall  be  replaced  with 
better.  The  result  will  be  that,  instead  of  feeling  that  time  has 
been  lost  in  merely  remedying  an  accident,  there  will  be  a  feeling 
of  congratulation  that  that  very  mischance  was  converted  to  an 
advantage. 

Again,  instead  of  falling  into  a  routine  of  work  from  time  to 
time,  consider  whether  there  may  not  be  some  better  mode  of 
operating,  and  if  a  probable  improvement  suggest  itself,  or  is 
suggested  by  others,  give  it  a  fair  trial. 

On  the  other  hand,  beware  of  capriciously  changing  about  from 
one  process  to  another.  There  are  often  several  good  ways  of 
doing  some  one  thing,  any  one  of  which  well  done  is  better  than 
any  other  unskilfully  carried  out.  It  is  best,  therefore,  to  acquire 
a  thorough  knowledge  of  some  good  means  of  managing  each 
operation — this  gives  firm  foothold.  Experiments  in  other  di¬ 
rections  then  will  be  compared  carefully  with  the  regular  plan, 


A  FEW  GENERAL  RULES  FOR  BEGINNERS. 


51 


which  will  never  be  abandoned  until  by  repeated  trial  the  new 
method  has  shown  itself*  distinctly  superior. 

30.  Success  will  very  often  depend  upon  the  willingness  to 
make  another  trial,  for  want  of  which  many  barely  fail. 

31.  Finally,  the  beginner  in  Landscape  Photography  is  earnestly 
recommended  to  act  upon  a  definite  system.  For  example,  let 
him  not  run  from  one  lens  to  another,  but  rather,  having  provided 
himself  with  one  thoroughly  good  one,  let  him  study  out  its  capa¬ 
bilities  and  learn  exactly  how  to  use  it.  Different  lenses  work 
so  differently,  that,  to  the  beginner,  they  are  very  confusing,  and 
tend  to  conceal  from  him  the  sources  of  the  mistakes  and  faults 
that  he  must  necessarily  make.  Only  in  one  way  can  he  usefully 
employ  himself  with  several  lenses,  and  that  is  by  using  them  in 
succession  to  take  the  same  view,  and  observing  and  studying 
closely  the  differences  in  the  results. 

The  secret  of  success  lies  in  taking  up  separately  each  different 
portion  of  the  work  and  mastering  it  by  careful  study.  First 
take  the  view  from  any  convenient  window  until  you  can  do  it 
with  regular  and  complete  success.  Next  select  some  attractive 
landscape,  and  try  it  upon  different  points,  and  with  varying 
lights,  and  longer  and  shorter  exposures,  until  you  have  done 
with  it  the  best  that  it  admits  of,  and  until  you  know  why  such  a 
result  is  the  best  that  can  be  attained.  One  such  piece  of  nega¬ 
tive-making,  worked  thoroughly  out,  will  teach  as  much  as  thrice 
the  time  spent  in  random  view-taking.  The  student  should  bear 
steadily  in  mind  that  whilst  a  thoroughly  good  negative  is  very 
valuable,  there  is  nothing  more  worthless  than  a  tolerable  one. 
A  tolerable  negative  is  not  worth  the  trouble  of  printing,  and  is 
consequently  worth  nothing  at  all. 


PART  II. 


PHOTOGRAPHIC  OPTICS  AND  THEORY  OF 
PERSPECTIVE. 


CHAPTER  I. 

GENERAL  OPTICS. 

§  1. — Reflection  and  Refraction. 

When  a  ray  of  light  (this  expression  will  be  more  convenient, 
although  wave  of  light  would  be  more  correct)  falls  upon  any 
surface,  a  part  is  reflected  and  a  part  transmitted. 

Let  the  ray  A  0  (Fig.  13)  pass  from  the  rarer  medium  on  one 
side  of  the  surface  E  F  into  the  denser  on  the  other ;  for  example, 

out  of  air  into  glass.  Part  of  the 
ray  will  be  reflected  and  part  re¬ 
fracted.  In  order  to  study  these 
phenomena,  we  draw  a  line  per¬ 
pendicular  to  the  surface  E  F  at 
the  point  of  incidence  0.  This 
line  N 0  is  the  normal ,  and  the 
angle  A  0  N  between  the  incident 
ray  and  the  normal  is  the  angle 
of  incidence. 

We  find  that  the  reflected  ray  makes  the  angle  of  reflection  BON 
equal  to  the  angle  of  incidence  AON. 

The  refracted  ray  is  bent  out  of  its  course  towards  the  normal. 
In  place  of  continuing  on  in  its  direction  A  0  f  it  is  deflected 
towards  the  normal  N N\  in  some  direction  0  i?,  and  the  quan¬ 
tity  of  deflection  depends  upon  the  character  of  the  substance. 
The  greater  the  deflection,  the  higher  the  refractive  power  is  said 
to  be. 

In  the  foregoing  we  have  considered  the  case  of  a  ray  passing 


REFRACTION. 


53 


from  a  rarer  medium  into  a  denser.  In  the  converse  case  the 
converse  result  takes  place.  If  in  the  above  figure  we  suppose 
the  directions  to  be  reversed,  and  that  the  ray  R  0  passes  at  0 
from  the  denser  medium  into  the  rarer  above  it,  then  the  ray  R  0 
will  be  bent  away  from  the  normal  to  precisely  the  same  extent, 
and  will  follow  the  path  0  A. 

It  therefore  follows  from  this  that  when  a  ray  passes  from  a 
rarer  medium  into  a  denser,  and  then  through  the  denser  again 
into  the  rarer,  it  will  emerge  in  a  direction  parallel  to  that  in  which 
it  entered,  provided  that  the  denser  medium  has  parallel  sides. 

The  ray  A  D  (Fig.  14),  in  passing  through  the  denser  medium, 
takes  the  course  D  B,  being  deflected  towards  the  normal,  and, 
on  emerging,  again  assumes  a  direction  B  G  parallel  to  A  D. 


Fig.  14.  Fig.  15. 


But  if  the  sides  of  the  denser  medium  are  not  parallel,  the  ray 
will  not  emerge  from  the  second  surface  parallel  to  its  first  direc¬ 
tion.  Thus  the  sides  OB,  B F  (Fig.  15)  of  the  denser  medium 
not  being  parallel,  the  ray  A  0,  in  passing  through  the  surface 
B  F,  takes  a  different  direction  B  C. 

Different  substances  refract  the  rays  of  light  very  differently, 
and  are  therefore  said  to  differ  in  refractive  power. 

We  have  a  very  convenient  method  of  measuring  refractive 
power,  which  is  as  follows: — - 

In  Fig.  16  let  Sr  S"  be  the  boundary  line  between  an  upper  and 
rarer  substance  and  a  lower  and  denser  one.  Let  any  ray  of  light 
R  0  pass  at  0  out  of  the  rarer  into  the  denser,  and  let  the  line 
0  R'  represent  its  deflected  direction. 

With  any  distance  0  A  as  a  radius,  draw  the  curve  A  Nr  R\ 
Draw  at  the  point  0  the  normal  N  N',  and  from  the  intersection 
A  let  drop  the  perpendicular  A  tS,  similarly  from  Rr  the  perpen¬ 
dicular  R'  S. 

A  S  will  be  the  sine  of  the  angle  of  incidence  and  Rr  S  the  sine 


54 


GENERAL  OPTICS. 


of  tlie  angle  of  refraction.  Each 
of  these  angles  will  be  conve¬ 
niently  measured  by  its  sine. 

Now  it  is  found  that  when  any 
two  given  substances  constitute 
the  rarer  and  the  denser  me¬ 
dium,  the  proportion  between 
the  lengths  of  A  S  and  R'  S  is 
invariable,  whatever  be  the  an¬ 
gle  of  incidence.  If  the  upper 
medium  be  air  and  the  lower  a 
certain  quality  of  glass,  the  sine  of  refraction  R '  S  will  always  be 
exactly  two-thirds  the  sine  of  incidence  A  S,  let  the  ray  fall  upon 
the  dividing  line  S'  S"  at  what  angle  it  may. 

The  ratio  of  the  sines  is  then  invariable  for  any  given  substance, 
and  this  ratio  is  called  the  index  of  refraction.  In  the  case  just 
mentioned  A  S  being  to  R'  S  always  as  3  to  2,  the  index  of  re¬ 
fraction  of  such  glass  is  said  to  be  §  or  1.5. 

The  path  which  will  be  taken  by  any  ray  in  passing  from  one 
medium  into  another  can  easily  he  traced  as  follows :  Let  the  ray 
R  0  pass  out  of  air  (or  rather  out  of  a  vacuum,  but  the  difference 
is  unimportant  here)  into  glass  of  refractive  power  1.5.  Draw 
the  normal  N Nf  through  the  point  of  incidence  and  perpendicu¬ 
lar  to  the  surface.  Set  off  any  distance  0  S' ,  and,  taking  this  as 
unity,  make  0  S"  equal  to  the  index  of  refraction.  In  this  case 
0  S"  will  stand  to  0  S'  in  the  proportion  of  1.5  to  1.  Draw  the 
perpendiculars  S'  R ',  S"  A.  Putting  one  leg  of  a  compass  at  0 
and  the  other  at  A  (the  intersection  of  S"  A  with  0  R)  draw  the 
curve  A  R' ,  the  intersection  of  this  curve  with  S'  R'  when  con¬ 
nected  with  0  gives  the  path  of  the  refracted  ray. 

§  2. — Dispersion. 

In  the  foregoing  section  we  have  reasoned  as  if  light  were 
homogeneous.  But  white  light  is  made  up  of  rays  of  very  differ¬ 
ent  refrangibility,  so  that  when  a  ray  of  white  light  A  B  (Fig.  17) 
passes  at  B  into  the  denser  medium  bounded  by  the  line  B  (7, 
these  rays  are  differently  affected.  The  more  refrangible  rays 
are  bent  more  out  of  their  course,  following  the  direction  B  F\ 
the  less  take  the  direction  B  E. 

On  reaching  the  second  surface  B  B ,  if  this  surface  is  not 


Fig.  16. 


DISPERSION. 


55 


parallel  to  the  first,  but  inclined  to  it,  these  different  rays  will 
have  their  divergence  greatly  increased,  and  will  be  spread  out 
as  there  represented. 


Fig.  17. 


We  find  that  a  difference  of  color  accompanies  a  difference  of 
refrangibility,  the  most  refrangible  being  violet,  and  so  proceeding 
in  the  order,  violet,  indigo,  blue,  green,  yellow,  orange,  and  red. 
Under  very  favorable  circumstances,  and  with  well-exercised  eyes, 
a  commencing  disposition  to  repeat  this  gamut,  like  octaves  in 
musical  sounds,  is  observable,  far  beyond  the  red  a  crimson  tint 
has  been  seen,  and  beyond  the  violet,  a  lavender. 

But,  independently  of  these,  the  existence  of  non-luminous 
influences  beyond  the  limits  of  the  visible  spectrum  is  easily 
detected.  Beyond  the  red  rays,  rays  of  dark  heat  are  made 
evident  by  the  thermometer,  and  beyond  the  violet  there  exists 
rays  also  invisible,  but  having  a  powerful  chemical  effect,  so  that 
in  a  portion  of  space  completely  dark,  sensitive  paper  is  rapidly 
impressed. 

Whilst  rays,  invisible  to  our  eyes,  are  thus  capable  of  exerting 
powerful  actinic  action,  other  rays,  plainly  and  even  brilliantly 
visible,  exercise  little  or  no  actinic  influence.  The  yellow  and 
red  rays,  in  which  the  chief  illuminating  power  of  light  resides, 
scarcely  act  upon  sensitive  substances.  The  green  rays  exert  an 
influence  on  some  and  not  on  others. 

It  is  not  a  little  remarkable  that  sulphate  of  quinine  possesses 
the  power  of  lowering  the  refrangibility  of  the  rays  beyond  the 
violet,  and  thus  rendering  them  visible  to  our  eyes.  If  sulphate 
of  quinine  be  dissolved  in  water  acidulated  by  sulphuric  acid,  and 
the  solution  be  placed  in  the  dark  rays  beyond  the  violet,  these 
become  visibly  blue. 


56 


GENERAL  OPTICS. 


CHAPTER  II. 

OF  LENSES.  t 

$  1. — Nature  of  Lenses. 

A  lens  may  be  plane  on  one  side  and  convex  on  the  other — 
plano-convex.  (Fig.  18.)  Plane  on  one  side  and  concave  on  the 
other-*-plano-concave.  (Fig.  19.)  Convex  on  both  sides — double 
convex.  (Fig.  20.)  Concave  on  both  sides— double  concave. 

Fig.  18.  19.  20.  21.  22.  28. 


(Fig.  21.)  Concave  on  one  side  and  convex  on  the  other — menis¬ 
cus.  The  meniscus  may  be  of  two  sorts.  If  the  radius  of  the 
convex  side  is  the  shorter,  the  lens  is  thickest  in  the  middle,  and 
is  called  a  positive  meniscus.  (Fig.  22.)  If  the  concave  curve  has 
the  shorter  radius,  the  meniscus  is  thickest  at  the  edges,  and  is 
termed  a  negative  meniscus.  (Fig.  23.) 

To  understand  the  action  of  a  lens  on  rays  of  light,  let  us  select 

a  plano-convex  lens  and  con¬ 
sider  its  properties. 

When  a  ray  of  light  L  A  falls 
upon  any  curved  surface  at  any 
point  A,  we  draw  a  tangent  B  0 
at  the  point  A,  and  we  may 
then  consider  the  solid  body 
A  6r,  as  far  as  the  ray  A  A  is 
considered,  not  as  a  body  hav- 
a  curved  surface,  but  as  a  prism 
B  G  Cy  for  it  will  act  towards  the  ray  L  A  precisely  as  if  it  were 
such  a  prism.  The  ray  L  A  passing  out  of  it  will  be  sent  away 
from  the  normal  in  the  direction  A  AT,  and  will  intersect  the  axis 
D  H  at  a  point  H. 


Fig.  24. 


OF  LENSES. 


57 


Let  us  now  consider  several  rays  of  light  L  L\  &c.  (Fig.  25.) 
L  strikes  at  the  centre  of  the  curve,  where  the  tangent  is  parallel 
to  the  plane  side  A  B ,  and  is  therefore  influenced  precisely  as  if 


Fig.  25. 


it  passed  through  a  piece  of  plane  glass,  and  emerges  in  the  same 
right  line.  L'  is  bent  on  leaving  the  curved  surface,  and  tends 
towards  F.  Other  rays  strike  the  curve  still  higher  from  the  axis, 
where  the  tangents  are  still  more  inclined,  and  are  therefore  still 
more  deflected.  This  greater  deflection  makes  up  for  the  fact 
that  the  original  path  of  that  ray  was  farther  from  the  central 
ray,  and  thus  all  the  rays  approximately  tend  to  gather  together 
at  a  point  F)  called  the  focus. 

What  is  true  of  the  plano-convex  lens,  is  true  of  all  lenses  that 
are  thickest  in  the  centre,  of  double  convex  and  of  positive 
meniscus  lenses.  Those  lenses  which  are  thinnest  at  the  centre 
are  called  negative.  They  do  not  collect  parallel  rays  to  a  focal 
point,  but  cause  them  to  diverge.  They  have  no  real  focus,  but 
only  a  virtual  one.  Such  lenses  taken  alone  would  be  of  no  use 
in  photography,  but  they  are  often  employed  in  connection  with 
others. 

If  matters  passed  exactly  in  the  manner  above  described,  the 
construction  of  photographic  objectives  would  be  far  more  simple 
than  it  is.  But  the  spherical  lenses  which  we  use  are  liable  to 
faults,  which  will  next  be  considered. 

5 


58 


GENERAL  OPTICS. 


CHAPTER  III. 

FAULTS  INCIDENT  TO  SPHERICAL  LENSES. 

There  are  five  distinct  sources  of  inaccuracy  in  the  image 
formed  by  a  spherical  lens.  These  are,  Spherical  Aberration, 
Chromatic  Aberration,  Astigmation,  Curyature  of  the 
Field,  and  Distortion. 

$  1. — Spherical  Aberration  and  the  Modes  of  Remedying  it. 

All  lenses  in  use  at  the  present  day  have  their  curves,  parts  of 
spheres.  How  it  is  a  property  of  all  spherical  curves  A  B ,  Fig. 
26,  that  they  do  not  bring  the  rays  exactly  to  a  point  at  F.  Just 
in  proportion  as  the  parallel  ray  A'  is  further  from  the  central 
axis  A,  so  is  that  ray,  after  passing  through  the  lens,  brought 
down  to  the  central  axis  at  a  point  nearer  to  the  lens.  The  focal 
length  Fr  for  the  ray  Lf  is  shorter  than  the  length  of  F  for  the 
ray  A,  and  so  on. 

It  will  be  seen,  then,  that  for  the  spherically  curved  lens  A  B 
there  is  no  real  focus,  but  a  succession  of  foci  all  the  way  from 
A7  to  F\  and  although  the  fault  is  intentionally  exaggerated  in  the 
figure,  it  is  still  so  great  as  imperatively  to  require  attention. 


Spherical  aberration  may  be  destroyed,  or  at  least  diminished, 
in  two  ways.  Either  lenses  may  be  so  combined  that  their  aber¬ 
rations  will  be  in  opposite  directions,  and  so  compensate  and 
destroy  each  other,  or  else  diaphragms  may  be  employed. 

Correction  by  Diaphragms. — The  ray  R "  A  which  would  come 


FAULTS  INCIDENT  TO  SPHERICAL  LENSES.  59 

to  a  focus  at  a  point  F'  nearer  to  the  lens  than  F  (see  Figs.  26 
and  27)  is  cut  off  by  the  diaphragm  CD.  We  thus  greatly  in- 

Fig.  27. 


C  a 


/?"  _ J _ 

-\ 

r 

f  f\ 

\ 

R  G 

J 

1  "  ' 

D  B 


crease  the  sharpness  of  definition  by  the  use  of  a  stop,  though  of 
course  at  a  great  sacrifice  of  light.  Thus,  if  the  lens  is  two  inches 
in  diameter,  and  the  aperture  of  the  diaphragm  is  a  quarter  of  an 
inch,  then,  as  the  areas  of  circles  are  at  the  squares  of  their  dia¬ 
meters,  the  loss  of  light  is  |J,  or  only  one  sixty-fourth  part  of 
the  whole  light  which  would  reach  the  sensitive  film,  if  a  full 
aperture  could  be  employed,  is  left  available. 

Although  this  loss  of  light  is  a  most  serious  evil,  it  is  necessa¬ 
rily  submitted  to,  and  we  gain  that  the  image,  before  dull  and 
hazy,  becomes  at  once  sharp  and  crisp.  Before,  the  lens  seemed 
to  have  no  true  focus;  now,  for  any  given  object,  the  focus  can 
be  found  with  exactitude. 

§  2. — Chromatic  Aberration  and  Mode  of  Correction. 

Spherical  aberration  is  independent  of  the  nature  of  the  light 
employed  ;  it  results  wholly  from  the  form  of  the  lens,  and  occurs 
even  with  homogeneous  light.  We  have  next  to  consider  a  sort 
of  aberration  arising  from  the  different  indices  of  refraction  of 
the  different  fays  of  which  white  light  is  composed. 

When  considering  the  subject  of  dispersion,  we  saw  that  when 
light  fell  upon  a  prism,  it  was  spread  out  into  a  spectrum,  in 
which  its  different  constituents  were  arranged  in  the  order  of 
their  refrangibility.  And  as  a  lens  may  be  taken  to  represent  a 
number  of  small  prisms,  it  follows  that  the  same  spreading  of 
the  colors  will  there  take  place. 

If,  as  in  Fig.  28,  a  perpendicular  ray  of  light  strikes  a  plano¬ 
convex  lens  at  A,  it  passes  into  it  unchanged;  but  at  B  the  dis¬ 
persion  of  the  rays  takes  place  according  to  their  refrangibility, 
and  the  focus  of  the  violet  rays  is  nearer  to  the  lens  than  that  of 
the  less  refrangible  rays  at  the  red  end  of  the  spectrum.  The 


60 


GENERAL  OPTICS. 


distance  between  these  two  foci  V  and  R  is  called  the  chromatic 
aberration,  which  in  the  figure  is  necessarily  exaggerated  for 
clearness. 

Fig.  28. 


This  fact  may  be  easily  rendered  visible  b y  holding  such  a  lens 
in  the  sunlight.  Rays  of  white  light  L  L  (Fig.  29)  are  divided, 

Fig.  29. 


L 


and  the  violet  rays  find  their  focus  at  V ,  the  red  at  P.  If  a 
white  screen  be  interposed  anywhere  between  the  lens  and  the 
point  I,  there  will  be  a  circular  image  of  the  sun  with  a  red 
border ;  beyond  I,  where  the  violet  rays  cross  the  red  and  pass 
outside,  the  image  will  have  a  violet  border.  The  distance  V P 
along  the  axis  between  the  foci  of  the  red  and  violet  is  termed 
the  longitudinal  aberration ,  and  that  at  II  the  lateral  aberration. 
II  is  the  place  at  which  the  least  circle  encloses  the  whole  of  the 
rays,  it  is  therefore  the  best  focus. 

To  understand  clearly  how  the  chromatic  aberration  is  cor¬ 
rected,  it  is  necessary  to  bear  in  mind  that  the  refractive  power  of 
substances  and  their  dispersive  power  are  not  proportionate  to  each 
other.  For  substances  may  exist  of  equal  refractive  power,  and 
different  dispersive,  and  conversely. 

Let  us,  then,  take  two  sorts  of  glasses,  and  construct  a  double 
convex  lens  of  that  sort  that  has  the  least  dispersive  power.  Next 
let  us  form  a  negative  lens  (i.  e.  one  thinnest  in  the  middle)  of  a 
sort  of  glass  having  a  much  greater  dispersive  power,  and  let  us 


FAULTS  INCIDENT  TO  SPHERICAL  LENSES. 


61 


Fi<r.  30. 


so  regulate  its  curves  that  it  shall  exactly  compensate  and  de¬ 
stroy  the  dispersion  of  the  first  lens  (by  introducing  an  equal  dis¬ 
persion  in  an  opposite  direction).  As  the 
negative  lens  had  a  higher  dispersive  power 
than  the  double  convex,  it  will,  whilst  re¬ 
moving  wholly  the  dispersion  of  the  latter, 
leave  it  a  residue  of  refraction.  So  that  the 
compound  lens  (Fig.  30),  although  its  disper¬ 
sive  power  has  been  destroyed,  is  still  capa¬ 
ble  of  converging  rays  to  the  focus.  This  is  now  an  achromatic  lens. 
It  is  not  necessary  that  the  negative  lens  should  be  double  concave, 
as  in  Fig.  30.  It  may  be  plano-concave,  and  may  be  combined 
with  a  plano-convex  (Fig.  31),  or  a  double  convex  (Fig.  32). 


§  3. — Astigmation. 

Astigmation  is  produced  in  those  pencils  of  light  that  fall 
obliquely  upon  the  lens. 

Let  G  D  E  F  represent  the  face  of  a  lens,  not  a  section  as 
usually  shown  in  the  figures.  Let  R  R ,  R'  Rr,  R"  be  rays  of 


Fig.  33. 


light  coming  from  an  object  so  distant  that  they  are  parallel. 
Let  the  central  ray  R"  pass  through  the  optical  centre  of  the 
lens;  it  will  emerge  parallel  to  its  original  direction;  its  prolonga¬ 
tion  in  the  direction  p  will  constitute  a  secondary  axis.  Let  E  F 


62 


GENERAL  OPTICS. 


be  a  diameter  of  the  lens,  perpendicular  to  the  axial  ray  R" , 
and  C  D  another  diameter  at  right  angles  with  the  first.  Now 
the  rays  R'  Rr,  which  reach  the  lens  at  E  and  F ,  strike  it  under 
absolutely  the  same  conditions.  They  will,  therefore,  undergo 
equal  refraction,  and  will  meet  the  secondary  axis  at  some 
point  P'. 

But  this  is  not  at  all  the  case  with  the  rays  R  R,  which  fall  on 
the  ends  of  the  other  diameter  CP.  They  will  strike  the  curved 
surface  of  the  lens  under  very  unequal  angles,  and  will  be  very 
differently  refracted.  R  D  will  reach  the  axis  at  some  point  P, 
R  G  at  some  point  p.1 

But  the  use  of  a  diaphragm  cuts  off  R  D  and  the  neighboring 
rays.  Of  the  rays  that  are  left,  R  G  and  the  neighboring  rays 
have  their  focus  aty>,  whilst  R'  E,  Rf  Phave  their  focus  at  pr. 

It  follows,  therefore,  that  oblique  pencils  have  no  true  focus. 
For  if  p  be  taken  as  the  focus,  then  the  rays  P'  E,  R'  F  will  have 
crossed  atp>',  and  atp  they  will  have  widened  out  again,  and  the 
image  of  the  radiant  point,  instead  of  being  a  point,  will  be  an 
ellipse,  having  its  major  diameter  in  the  direction  E  F.  Con¬ 
versely,  ifp'  be  taken  as  the  focus,  R  G  and  the  neighboring  rays 
will  not  have  converged  to  a  focus,  and  their  section  on  the  focus¬ 
sing  screen  will  form  an  ellipse,  having  its  major  diameter  in 
the  direction  G D.  In  neither  case  will  the  point  have  its  image 
as  a  point,  hence  the  name  astigmation.  (a,  no,  and  point). 

The  image  of  the  point  will  appear  as  an  ellipse,  whose  greatest 
diameter  will  change  its  direction  according  as  the  focussing 
screen  is  farther  or  nearer  to  the  lens. 

Rays  incident  perpendicularly  upon  the  lens,  do  not  produce 
astigmation.  If,  then,  we  examine  the  case  of  a  pair  of  lenses 
having  convex  surfaces  outside,  and  a  stop  between  them,  we 
shall  see  that  if  this  stop  be  placed  at  the  centre  of  curvature  of 
the  outside  surfaces,  then  only  rays  of  incidence  nearly  perpen¬ 
dicular  to  the  surfaces  of  the  lenses  will  be  permitted  to  pass 
through  the  stop.  Lenses  with  central  stops,  will  have  less  or 
more  astigmation,  according  as  their  central  stop  corresponds 
more  or  less  nearly  with  the  centre  of  curvature,  and  as  its  open¬ 
ing  is  smaller. 

1  The  unequal  refraction  of  B  C,  R  D  is  the  cause  of  coma,  which  will  be 
presently  treated  of. 


FAULTS  INCIDENT  TO  SPHERICAL  LENSES. 


63 


In  the  single  meniscus  view  lens,  the  astigmation  will  be  less 
in  proportion  to  the  depth  of  concavity  of  the  front  surface.  It 
will  also  be  controlled  by  the  position  of  the  front  stop.  The 
nearer  this  is  placed  to  the  centre  of  curvature  of  the  front  con¬ 
cave  surface,  the  more  nearly  will  the  incidences  be  perpendicu¬ 
lar,  and  consequently 

the  less  the  astigma-  Fig.  s4- 

tion. 

Coma.  —  Spherical 
aberration  is  much 
more  easity  removed 
for  direct  rays  than 
for  those  that  strike 
the  lens  in  an  oblique 
direction.  Let  the 
rays  R  R'  R"  strike 
the  plano-convex  lens 
in  an  oblique  direc¬ 
tion.  One  ray,  R\ 
which,  after  refraction  at  the  first  surface  of  the  lens,  passes 
through  the  optic  centre  (7,  emerges  in  a  direction  parallel  to 
that  which  it  originally  took.  This  line  C  Pf  is  the  axis  of  the 
refracted  pencil.  The  ray  R"  meets  the  axis  at  P,  whereas  the 
ray  R  meets  it  at  P'  farther  on.  Thus  whilst  the  rays 
corresponding  with  R  are  gathered  at  the  point  P',  Fig.  35. 
those  corresponding  with  R”  are  spread  out  below  it 
constituting  coma.  (Fig.  35.) 

This  incorrectness,  like  so  many  others,  is  kept 
within  bounds  by  the  use  of  the  diaphragm,  which  in 
the  above  case  would  cut  off  the  ray  R ,  and  permit  only  such 
to  pass  as  would  converge  on  the  axis  O  P  to  a  single  point,  P, 
or  to  a  sufficiently  near  approximation. 

§  4. — Curvature  of  the  Field. 

If  we  suppose  an  object  of  some  size  placed  before  a  lens,  we 
shall  find  that  its  extremities  do  not  come  to  focus  on  the  same 
plane  as  its  centre. 

The  arrow  C  is  supposed  to  be  so  distant  that  its  ends  and 
centre  may  be  regarded  as  equally  far  removed  from  the  lens. 
Now  if  the  centre  of  the  arrow  G  has  focus  at  G\  its  extremities 
will  have  their  focus  not  in  a  plane  perpendicular  to  the  axis  of 


64 


GENERAL  OPTICS. 


Fig.  36. 


the  lens,  but  at  points  nearer  to  the 
lens.  The  whole  image,  therefore, 
will  not  fall  upon  a  plane,  but  upon 
a  concave  surface.  As  it  is  necessary 
that  it  should  be  rendered  flat,  we 
shall  consider  the  means  of  doing 
this  by  the  conjoint  operation  of  the 
diaphragm  and  the  correction  of  the  lens. 

Diaphragms. — If  a  diaphragm  or  stop  were  placed  immediately 
in  contact  with  a  lens,  it  would  virtually  reduce  the  lens  to  one 
the  size  of  the  diaphragm.  But  the  diaphragm  is  always  placed 
some  distance  away,  and  then  every  part  of  the  lens  concurs  in 
forming  the  picture,  but  each  part  is  only  permitted  to  act  upon 
those  rays  for  which  it  is  intended. 


Fig.  37. 


By  the  interposition  of  the  diaphragm,  the  dotted  oblique  ray, 
for  example,  which  would  reach  its  focus  at  a  much  nearer  point, 
is  cut  off*,  and  only  those  rays  are  permitted  to  pass  which  meet 
at  a  focus  as  nearly  as  possible  in  the  plane  in  which  the  central 
rays  find  their  focus  at  F.  Here  is  at  once  a  valuable  approxima¬ 
tion  towards  a  plane  field. 

Moreover,  by  virtue  of  the  stop  the  rays  which  form  the  image 
meet  with  a  very  small  angle,  and  it  is  evident  that  the  focussing 
screen  may  be  brought  into  such  a  position  that  all  parts  of  the 
image  will  be  very  good  focus  at  the  same  time. 

This  is  flattening  the  field  by  use  of  the  diaphragm. 

Correction. — But  the  field  may  also  be  flattened  in  the  same 
manner  that  the  correction  for  chromatic  aberration  is  applied. 


FAULTS  INCIDENT  TO  SPHERICAL  LENSES. 


65 


In  the  simple  lens  the  field  is  very  curved.  If  we  now  add  the 
correcting  negative  lens  to  remove  the  color,  we  shall  lengthen 
out  the  oblique  pencils  more  than  the  central. 

This  is  flattening  the  field  by  correction  of  the  lens. 


%  5. — Distortion. 

The  mathematical  conception  of  a  lens  regards  it  as  consisting 
merely  of  its  bounding  planes,  and  destitute  of  thickness.  If 
lenses  actually  possessed  this  form,  the  images  produced  by  them 
would  correspond  strictly  with  the  principles  already  laid  down. 
But  all  lenses  necessarily  possessing  a  definite  thickness,  the  image 
is  thereby  deformed,  unless  special  measures  be  taken  to  correct 
such  distortion. 

Every  right  line,  no  matter  what  be  its  inclination,  if  it  be 
directly  in  front  of  the  lens,  so  that  the  prolongation  of  the  axis 
of  the  lens  passes  through  it,  is  imaged  on  the  screen  as  a  right 
line,  whether  perpendicular,  horizontal,  or  inclined,  because  of  its 
symmetrical  position  with  respect  to  the  different  parts  of  the  lens. 

But  if  the  line  be  not  symmetrically  placed,  that  is,  if  the  pro¬ 
longation  of  the  axis  of  the  lens  do  not  pass  through  it,  then  the 
image  of  such  a  right  line  will  be  curved,  with  its  concavity 
turned  towards  the  axis  of  the  lens,  and  a  square, 
for  example,  will  be  represented  as  in  Fig.  38. 

This  is  termed  barrel  distortion ,  and  is  seen  in 
the  single  view  lens. 

The  position  of  the  diaphragm  has  necessarily 
a  strong  influence  on  distortion.  When  the  dia¬ 
phragm  is  in  front  of  the  lens,  as  in  the  case 
of  the  view  lens,  the  crossing  of  the  rays  takes 
place  in  front  of  the  lens,  and  the  lower  part  of  the  lens  receives 
the  rays  from  the  upper  part  of  the  object,  and  the  distortion  is 
barrel-shaped.  If  the  diaphragm  be  placed  behind  the  lens,  the 
crossing  of  the  rays  takes  place  behind  the  lens,  and  the  lower 
part  of  the  lens  receives  the  rays  from  the  lower  part  of  the  ob¬ 
ject.  If  now  we  take  the  case  of  two  lenses  with  a  stop  between, 
as  in  photographic  doublets,  the  one  compensates  the  other,  and 
the  distortion  disappears  completely  if  the  lenses  be  exactly 
similar  and  the  stop  be  placed  equidistant  from  each. 

Falling  off  of  Intensity  at  Edges. — In  addition  to  the  foregoing 
faults  incident  to  lenses  there  is  the  defect  introduced  by  the  dia- 


Fig.  38. 


66 


GENERAL  OPTICS. 


Fig-  39.  phragm  that  the  light  is  strongest  at  the 

centre,  and  falls  off  at  the  edges  instead 
of  the  illumination  being  everywhere 
equal. 

For  if  D  D  be  a  diaphragm,  it  is  evi¬ 
dent  that  the  pencil  of  rays  that  enter  it 
at  right  angles  will  be  much  larger  than 
the  pencils  that  take  an  inclined  posi¬ 
tion,  as  represented  by  the  dotted  rays. 
The  diminution  of  light  in  the  pencils 
from  the  sky,  is  rather  an  advantage 
than  otherwise ;  but  the  contrary  is  the 
case  with  the  pencils  from  the  fore¬ 
ground. 

Several  ingenious  contrivances  have 
been  made  to  counteract  this  tendency. 
Thus  a  conical  piece  is  arranged  to 
set  in  the  opening  of  the  diaphragm 
D  D,  within  it  is  an  inclined  diaphragm. 
This  evidently  allows  a  larger  pencil  to 
pass  from  the  foreground  than  the  centre, 
and  the  pencil  admitted  from  the  sky  is  still  smaller.  With 
badly  illuminated  foregrounds  this  arrangement  is  advantageous, 
but  in  ordinary  landscapes  the  distribution  of  light  is  found  to 
be  sufficiently  good  in  the  regular  image. 


CHAPTER  IY. 

FOCAL  LENGTHS  OF  LENSES. 

§  1. — Images  of  External  Objects. 

If  an  opening  be  made  in  a  shutter  A  of  a  dark  room,  there 
will  be  formed  on  the  opposite  wall  an  image  of  external  objects. 
The  rays  of  light  coming  from  an  object  B  0  will  cross  each  other 
at  the  opening  A ;  will  form  an  image  E  D  on  the  opposite  wall, 
which  image  will  have  the  following  characteristics: — 

It  will  be  reversed ,  because  the  rays  cross  at  A,  and  that  which 
was  lowest  (0)  in  the  object,  becomes  uppermost  (E)  in  the  image. 


FOCAL  LENGTHS  OF  LENSES. 


67 


If  the  opening  A  he  small ,  the  image  Fig.  41. 

will  be  very  faint,  but  moderately 
sharp. 

If  the  opening  he  large)  the  image 
will  be  better  lighted,  but  will  be 
confused. 

There  will  he  no  focus.  E  D  may 
be  at  any  distance  from  A. 

The  fact  that  the  confusion  of  the  image  can  only  be  removed 
by  an  excessive  diminution1  of  the  opening,  and  consequent  re¬ 
duction  of  the  light,  renders  it  useless  for  photography.  The 
cause  of  this  confusion  is  shown  in  .Fig.  42.  Let  P  be  any  point 


Fig.  42. 


of  any  distant  object,  as  the  point  C  of  the  arrow  in  the  preced¬ 
ing  figure.  The  rays  that  emerge  from  it,  after  passing  through 
the  opening  A  B ,  are  spread  out  upon  the  wall  at  A'  Bf ,  whereas 
they  should  be  collected  at  the  point  Pf. 

This  collecting  of  the  rays  and  conveying  them  to  the  point 
P'  is  effected  by  placing  a  lens  at  the  opening  A  B. 

But  now  a  new  condition  comes  in  with  the  lens.  Without  it 
images  were  formed  though  the  wall  were  at  any  distance  from 
the  opening.  But  with  the  lens  the  surface  that  receives  the 
image  must  be  at  a  fixed  distance  from  the  lens.  This  distance 
is  its  focal  length.  Measured  from  the  back  surface  of  the  lens, 
it  is  called  the  “back  focus,”  an  extremely  rough  and  erroneous 
mode  of  measurement.  Measured  from  the  true  point  (the  centre 
of  emission,  hereafter  explained)  it  is  the  absolute  focus,  also 
called  the  principal  focus  or  equivalent  focus. 


1  With  an  excessive  diminution  of  the  opening,  another  difficulty  presents 
itself,  that  of  diffraction.  The  lines  of  light  are  bent  by  the  edges  of  the 
opening. 


68 


GENERAL  OPTICS. 


If  rajs  from  an  external  object 
fall  upon  the  lens  A,  Fig.  43,  and 
an  image  is  formed  at  F \  the  focal 
length  would  be  the  distance  from 
F  to  the  lens  at  A,  supposing  the 
lens  to  have  no  thickness.  But 
as  all  lenses  have  thickness,  the 
question  immediately  arises,  from  what  point  or  part  of  the  lens 
or  lenses  is  the  measurement  to  be  taken  ? 

To  answer  this  question  it  is  necessary  that  we  should  get  a 
clear  idea  of  certain  remarkable  points  belonging  to  lenses,  single 
or  compound. 


Fig.  43. 


§  2. — Optital  Centre. 

All  lenses  have  a  remarkable  point,  to  which  the  above  name 
has  been  given.  All  lines  that  pass  through  the  lens  and  also 

through  this  point,  are  termed 
transversals ,  and  have  the  remarka¬ 
ble  property  that  all  rays  wrhich 
pass  through  the  lens  along  their 
path,  emerge  from  the  lens  parallel 
to  the  direction  in  which  they  en¬ 
tered  it. 

If  G  be  the  optic  centre,  any  line 
G  T  passing  through  it  will  be  a 
transversal.  If  now  a  ray  of  light  strike  the  lens  at  T  at  such 
an  angle  that  it  follows  the  path  T  F  it  will,  on  emerging  at  T\ 
follow  the  direction  T'  P  parallel  to  its  original  course. 

The  optical  centre  of  any  lens  is  easily  found.  It  is  only  ne¬ 
cessary  to  draw  parallel  radii  from  the  two  centres  of  curvature, 
to  connect  the  points  at  which  these  radii  meet  the  curves,  and 
to  prolong  this  line  till  it  intersects  the  axis. 

From  the  centre  G  of  the  one  curve  draw  any  radius  C  P. 
From  the  centre  G'  of  the  other  curve  draw  another  radius  Gf  R', 
parallel  to  the  first.  Connect  the  points  R  A',  prolonging,  if 
necessary,  the  line  of  connection  R  R\  till  it  intersects  the  axis 
G  G'.  The  point  of  intersection  0  will  be  the  optical  centre  of 
the  curve.  In  a  double  convex  lens  (Fig.  45)  the  optical  centre 
falls  inside  the  lens,  in  the  meniscus  (Fig.  46)  outside  of  it.  In  a 


Fi<2\  44. 


FOCAL  LENGTHS  OF  LENSES. 


63 


Fig.  45.  Fig.  46. 


double  convex  lens,  whose  surfaces  are  of  equal  curvature,  the 
optical  centre  will  coincide  with  the  centre  of  the  lens. 


§  3. — Centres  of  Admission  and  Emission. 


These  centres  play  too  important  a  part  in  photography  to  be 
here  passed  over. 

Let  0  be  the  optical  centre,  as  before,  of  a  double  convex  lens: 
then  any  lines  drawn  through  it,  as 
T  T \  T'  T\  are  transversals,  and  any 
rays  that  strike  the  points  T Tr  at  such 
angles  of  incidence  as  to  follow  the 
course  of  the  transversals,  will,  as  be¬ 
fore  explained,  emerge  at  T  T\  on  the 
other  side  of  the  lens,  and  follow  paths 
parallel  to  their  original  direction. 

If,  now,  all  the  entering  rays  be  pro¬ 
longed  in  their  original  directions,  they 
will  converge  to  a  point  P  on  the  axis 
of  the  lens.  This  is  the  centre  of  admis¬ 
sion.  If  the  emerging  rays  be  likewise 
prolonged,  they  will  meet  at  a  point  Pr. 

This  is  the  centre  of  emission. 

This  statement  is  rigorously  true  only  for  rays  very  nearly 
parallel  with  the  axis,  for  others  it  is  simply  an  approximation. 

Now,  if  in  Fig.  48  wre  have  a  bi¬ 
convex  lens,  and  A  B  be  an  object 
before  it,  C  D  its  image,  the  focal 
length  of  that  lens  must  be  mea¬ 
sured  from  P,  its  centre  of  emission, 
that  being  the  point  to  which  all 
the  rays,  G  P ,  PP,  D  P,  converge. 

And  similarly,  if  we  wish  to  take 


Fig.  48. 


c 

A 

i  ) 

A 

L 

>  < 

70 


GENERAL  OPTICS. 


into  account  the  distance  of  the  object  from  the  lens,  it  is  to  be 
computed  neither  from  the  exterior  of  the  lens,  nor  from  its 
centre,  but  from  the  centre  of  admission  P'.  Consequently, 
when  we  speak  of  the  conjugate  foci  belonging  to  the  lens  for  an 
object  A  B ,  and  its  image  CD,  these  focal  lengths  are  the  lines 
F'  P',  FP. 

In  the  following  figure  of  a  meniscus  lens,  the  transversals  are 
seen  centering  at  0,  the  optical  centre  of  the  lens.  The  respective 

rays  R  R  R  R  are  those  that 
undergoing  refraction  at  the 
surface  A  B ,  follow  the 
courses  of  the  transversals 
through  the  lens.  Emerg¬ 
ing  they  take  directions  T 
R',  &c.,  parallel  to  those 
which  they  originally  had, 
and  all  cut  the  axis  at  P , 
the  centre  of  emission. 

The  focal  distance  of  any 
object  in  front  of  this  lens 
will  therefore  be  measured 
to  the  centre  of  admission 
P' .  And  the  focal  distance  of  any  image  will  be  measured  from 
that  image  to  the  centre  of  emission  P. 

If  the  first  surface  of  the  lens  A  B  be  plane,  the  lens  becomes 
a  plano-convex,  and  the  points  0  and  P  both  recede  to  the  inter¬ 
section  of  the  curve  CD  with  the  axis  OP',  where  they  coincide. 

§  4. — To  Determine  Focal  Lengths  by  Actual  Measurement. 

Equivalent  Focus. — This  term  is  constantly  misapplied,  and 
most  of  the  popular  explanations  of  it  are  erroneous.  The 
whole  matter  is,  however,  very  simple,  and  may  be  explained  as 
follows : — 

In  a  plano-convex  with  its  plane  side  to  the  object,  the  focal 
length  is  the  distance  between  the  ground  glass  B'  (Fig.  50)  and 
the  bach  surface  of  the  lens,  therefore  A'  B'.  This  distance  is 
easy  to  measure,  and  offers  a  valuable  aid  towards  determining 
the  focal  lengths  of  other  forms  of  lens. 

Suppose  now  that  we  have  a  doublet  M  N,  0  P,  and  that  a  very 
distant  object  is  focussed  correctly  when  the  ground  glass  is  in 


Fig.  49. 


FOCUS  LENGTHS  OF  LENSES. 


71 


the  position  C  D.  The  question  Fig.  50. 

arises,  are  we  to  measure  from  the 
ground  glass  at  B  to  what  point  ? 
the  back  lens,  the  front  lens,  or 
what  point  between  ? 

Let  us  suppose  that  we  find  a 
plano-convex  lens  B  S,  which, 
when  placed  in  the  same  position 
as  the  doublet,  and  focussed  on 
the  same  distant  object,  makes  its 
image  C'  D'  exactly  the  same  size 
as  the  image  C  D  of  the  same  object 
given  by  the  doublet.  Then  these  lenses  have  the  same  equivalent 
focus ,  and  the  easily  measured  focal  length  A'  B'  of  the  plano¬ 
convex  is  also  the  true  (equivalent  or  absolute)  focal  length  of 
the  doublet.  The  rays  A  C,  A  D,  which  form  the  image  in  the 
case  of  the  doublet,  diverge  as  if  they  came  from  a  point  A,  which 
point  is  the  centre  of  emission. 

It  follows  from  the  foregoing  that  all  lenses  that  have  the  same 
equivalent  focus,  will,  when  focussed  on  some  distant  object, 
produce  images  of  it  that  have  the  same  size,  the  one  as  the  others. 

And  further,  which  is  important,  that  lenses  of  different  focal 
lengths  will,  when  focussed  on  the  same  distant  object,  produce 
images  of  it  whose  size  is  proportionate  to  the  respective  focal 
lengths. 

If  A  B,  Fig.  51,  be  any  distant  object :  different  lenses  placed 
at  L  will  give  images  of  it  having  different  sizes,  but  these  sizes 
will  always  be  proportional  to 

the  focal  length  P'  F,  P'  F',  &c.,  w  Fig.  51. 

and  will  be  larger  or  smaller 
in  the  exact  proportion  of  the 
focal  length  of  the  lens  that 
forms  them.  A  lens  having 
twice  the  focal  length  of  ano¬ 
ther,  will,  when  placed  in  the 
same  spot,  and  focussed  upon 

the  same  distant  object,  produce  an  image  having  twice  the  linear 
dimensions  of  the  image  given  by  the  first.  If,  therefore,  in 
order  to  find  the  focal  length  of  a  doublet,  we  compare  it  with 
a  plano-convex  as  in  Fig.  50,  it  is  not  essential  that  the  two 
should  give  images  of  the  same  size,  which  might  in  practice 


' '  f 

- 

72 


GENERAL  OPTICS. 


be  difficult  to  attain.  But  having  easily  measured  the  focal 
length  of  the  plano-convex,  we  simply  compare  the  size  of  the 
two  images,  the  proportion  between  which  establishes  the  focal 
length  of  the  doublet.  If  the  image  given  by  the  doublet  is 
one-fourth  longer,  we  know  that  its  focal  length  is  necessarily 
one-fourth  longer,  and  so  on.  And  having  thus  determined  the 
exact  focal  length  of  one  doublet,  we  may  use  it  (just  as  well  as 
the  plano-convex)  to  determine  the  focal  length  of  any  other  de¬ 
scription  of  lens,  by  the  same  system  of  comparing  the  linear 
dimensions  of  the  image  formed. 

Another  practical  method  of  determining  the  focal  length  of 
any  form  of  photographic  objective  has  been  indicated  by  Mr. 
Grubb. 

Mark  the  centre  of  the  focussing  screen  by  drawing  diagonals 
from  opposite  corners.  Set  the  camera  on  a  large  sheet  of 
white  paper;  place  the  camera  so  that  the  images  of  two  well- 
marked  distant  points  shall  be  equally  distant,  one  on  each 
side  of  the  centre.  Measure  the  distance  of  these  two  points 
from  each  other  on  the  screen.  Now  turn  the  camera  so  that 
one  of  these  points  shall  fall  exactly  upon  the  centre.  Having 
done  this,  run  a  pencil  along  the  side  of  the  camera,  ruling  a 

lineon  the  paper  underneath.  Now 
turn  the  camera  around  again,  till 
the  other  point  falls  on  the  centre 
of  the  focussing  screen,  and  draw 
another  line  on  the  paper. 

Let  A  B  and  C  D  be  the  lines 
so  drawn;  continue  them  till  they 
meet  at  F.  Bisect  the  angle  AEG 
by  the  line  E  F.  At  any  point  F 
erect  the  perpendicular  F  G  equal 
to  half  the  length  of  the  space  measured  on  the  ground  glass  be¬ 
tween  the  points.  From  G  draw  G  E  parallel  to  A  B.  The 
distance  on  F  H  of  its  intersection  H  from  A  will  be  the  abso¬ 
lute  focal  length  of  the  objective  used. 

This  having  been  once  correctly  done  for  any  one  lens,  it  will 
serve  as  a  standard  for  the  easy  determination  of  others  by  the 
method  above  described.1 

1  Another  method  is  the  following :  Focus  two  objects,  so  that  their  images 
will  fall  upon  the  ground  glass  equally  distant  from  the  centre,  as  before  de¬ 
scribed  ;  then  measure  with  a  theodolite  the  angle  which  these  objects  subtend. 


Fig.  52. 


FOCAL  LENGTHS  OF  LENSES. 


73 


It  is  remarkable  that  the  method  of  determining  the  focal 
length  of  a  lens  by  focussing  an  object  so  that  the  size  of  its 
image  shall  be  equal  to  its  own,  and  then  taking  one-fourth  of 
the  distance  between  the  object  and  its  image  for  the  focal  length, 
after  having  been  repeatedly  shown  to  be  inaccurate,  has  been 
constantly  brought  forward  again.  The  error  lies  in  the  misap¬ 


plication  of  the  formula  j  =  -  4*  -  by  which  it  is  attempted  to 


afford  a  proof.  This  formula  neglects  the  thickness  of  the  lens, 
which,  in  compound  lenses  (i.  e.  doublets,  &c),  is  often  very  con¬ 
siderable,  and  thereby  introduces  an  error.  Nor  can  this  error 
be  avoided  by  computing  these  focal  distances  from  the  optical 
centre  of  the  lens,  since  they  must  be  computed  from  the  centres 
of  admission  and  emission  to  render  the  formula  applicable.1 


§  5. — To  Calculate  the  Focal  Length  of  a  Lens  from  its  Dimensions. 

In  the  following  formulae,  it  will  be  taken  for  granted  that  the 
lens  is  made  of  glass,  having  its  refractive  power  equal  to  1.5. 
The  more  general  expressions  will  be  given  in  foot-notes.  The 
focus  in  all  cases  is  determined  for  sunlight  or  parallel  rays  fall¬ 
ing  parallel  with  the  axis  of  the  lens.2 

In  the  case  of  a  glass  sphere  the  focal  length  is  1J  times  the 
radius,  measured  from  the  centre  of  the  sphere.  It  falls  there¬ 
fore  beyond  the  sphere  at  the  distance  of  half  the  radius  from 
the  surface.3 


Calling  this  angle  a,  and  d  the  distance  measured  on  the  ground  glass,  the  focal 
length  will  be  found  by  the  expression — 

d 

/=- - . 

2  tan— 

2 


1  If  it  were  required  to  make  a  correct  determination  by  the  method  of  fo¬ 
cussing  equal  size,  it  would  be  necessary  to  determine  for  any  lens  the  distance 
which  separates  its  centres  of  admission  and  of  emission.  Calling  this  S'  and 


the  distance  between  object  and  image,  D,  we  have  /= 


n±  s 

4~’ 


the  positive  sign 


applies  when  the  centres  cross  each  other,  the  negative  when  they  do  not,  as  in 
the  photographic  objectives. 

2  These  calculations  are  all  based  (except  when  otherwise  specified)  accord¬ 
ing  to  custom,  and  for  simplicity,  upon  the  supposition  that  the  lens  has  no 
thickness. 

8  The  general  expression  is  as  follows  :  Let  r  equal  index  of  refraction,  B  the 

r 

radius,  f  the  focal  length,  then  f—B jy 
6 


74 


GENERAL  OPTICS. 


Double  Convex  Lens} — If  the  curves  on  both  sides  are  equal, 
the  focal  length  will  be  equal  to  the  radius. 

If  unequal,  multiply  the  radii  together,  and  divide  by  half 
their  sum.  If  the  radii  are  respectively  5  and  7  inches,  the  focal 
length  will  be  3e5  inches  or  5§  inches. 

Plano-convex  Lens. — Where  the  plane  side  is  exposed,  the  focus 
will  be  twice  the  radius,  measured  from  the  convex  side.  Where 
the  rays  fall  on  the  convex  surface  §  the  thickness  of  the  lens 
must  be  deducted  from  twice  the  radius,  and  this  will  be  mea¬ 
sured  from  the  plane  side. 

Meniscus  Lens. — Multiply  the  radii,  and  divide  the  result  by 
half  the  distance  of  the  radii.  For  example,  if  a  meniscus  has 
its  positive  curve  with  a  radius  of  5  and  its  negative  7  inches,  its 


focal  length  will  be  y-/f7  "  or  35  inches. 

If  the  concave  surface  had  a  radius  of  5  and  the  convex  of  7, 

the  focus  would  be  the  same,  but 
it  would  be  a  virtual  focus ,  an  im¬ 
aginary  one  in  front  of  the  lens. 

So  in  Fig.  53,  the  parallel  rays 
ERR  are  spread  out  by  the 
negative  meniscus,  so  that  if  their 
direction  were  continued  back¬ 
wards,  they  would  meet  at  F:  the 
virtual  focus. 

Although  this  focus  has  only  an  imaginary  existence,  it  be¬ 
comes  important  in  compuffing  the  effect  of  introducing  a  negative 
lens,  as  in  several  forms  of  photographic  objectives. 


§6. — Focal  Lengths  of  Combined  Lenses  Computed  from  their 

Elements. 

Where  two  lenses  of  known  focal  length  are  combined  to¬ 
gether,  it  is  easy  to  determine  the  focal  length  of  the  combina¬ 
tion.  It  becomes  here  necessary,  however,  to  take  into  account 
the  distance  at  which  the  two  lenses  are  separated ,  as  the  focal 
length  always  increases  as  this  separation  increases. 

1  The  general  expression  for  the  focal  length  of  any  lens  in  terms  of  its  radii,  is 
2  RR' 

the  positive  sign  belonging  to  the  biconvex  lens,  the  negative  to  the 
meniscus. 


FOCAL  LENGTHS  OF  LENSES. 


75 


Add  the  two  focal  lengths  together,  and  subtract  the  distance 
of  separation.  Multiply  the  two  focal  lengths  together,  and  di¬ 
vide  this  last  quantity  by  the  first,  which  gives  the  focal  length.1 
This  formula,  which,  like  the  preceding,  depends  on  the  suppo¬ 
sition  that  glass  with  a  refractive  power  of  1.5  forms  the  material 
of  the  lenses,  is  that  which  is  employed  by  opticians  in  their 
calculations. 

Two  lenses  of  6  and  10  inches  focal  length  respectively,  sepa¬ 
rated  one  inch,  will  have  their  combined  focal  length 


or  4  inches. 

If  these  lenses  when  combined  are  to  have  a  focal  length  of  5 
inches,  this  can  be  effected  by  giving  them  a  separation  of  4 


inches,  because 


6x10 

16—4 


is  5  inches. 


§  7. — Conjugate  Foci. 

Up  to  the  present  point  we  have  considered  parallel  rays  only. 
But  when  divergent  or  convergent  rays  fall  upon  a  lens,  its  focal 
length  is  thereby  necessarily  altered. 

Thus  the  lens  A  B  having  its  focus  at  F  for  parallel  rays,  may 
have  it  at  D  for  diverging,  and  at  E  for  converging  rays. 


Fig.  54. 


If  Df  be  a  point  from  which  diverging  rays  emanate  and  these 
converge  again  after  passing  through  the  lens,  at  D,  these  two 
points  D  and  D\  are  termed  conjugate  foci.  If  D '  be  an  object, 
it  will  have  its  focus  at  D.  These  points  are  interchangeable, 
so  that  if  the  object  be  placed  at  D%  its  focus  will  be  at  D'. 


1  If  /  and  f'  are  the  respective  focal  lengths,  and  d  the 

ff 

tion,  then  the  combined  focus  will  ke^^r^- 


distance  of  separa- 


76 


GENERAL  OPTICS. 


Fig.  55. 


To  observe  this  better,  let  us  take 
a  plano-convex  lens,  with  its  plane 
side  to  the  object. 

The  object  Dr  has  its  focus  at  D. 
If  the  principal  focus  (that  for  paral¬ 
lel  rays)  be  called /,  and  the  distance 
Dr  G ,  u  and  G  D ,  v,  then  we  shall 
have  this  relation : — 


+ 


1 

-  or  v  — 
v 


■  A 

u— f 


This  equation  will  permit,  if  the  principal  focal  length  is 
known,  to  determine  the  position  of  the  image  D  of  any  object 
situated  at  any  point  B'.  If,  for  example,  the  lens  have  a  focus 
of  6  inches,  and  the  object  B '  is  10  feet  or  120  inches  off,  we  shall 
have — 


6x120  720 

“  120—6  ~  114 


6.315. 


The  focus  of  such  a  lens  will,  therefore,  be  a  little  over  three- 
tenths  of  an  inch  longer  for  an  object  at  the  distance  of  ten  feet, 
than  for  a  very  distant  object,  that  is  to  say,  for  parallel  rays. 

It  will  be  seen  that  this  formula  gives  a  very  simple  rule  for 
calculating  focal  lengths.  If  the  principal  or  absolute  focal  dis¬ 
tance  of  a  lens  be  known,  and  we  place  an  object  nearer  to  the 
lens,  and  require  to  know  what  will  be  the  focal  length  of  the 
lens  for  such  an  object,  we  have  only  to  take  these  two  quanti¬ 
ties — the  absolute  focal  length  and  the  distance  of  the  object. 
First  multiply  them  and  then  subtract  them,  and  divide  the  first 
number  by  the  second,  as  in  the  example  where  120  was  multi 
plied  by  6,  and  divided  by  120  less  6. 

It  is  a  very  important  point,  and  one  that  has  been  too  often 
overlooked  in  treating  the  subject  elementarily,  that  the  formula 

j  —  -  -f-  -  neglects  the  thickness  of  the  lens.  In  practice  it 

is  necessary  either  to  introduce  a  correction  for  this  quantity,1  or 


1  The  most  general  form  of  expression  for  conjugate  foci  is 

u  {  n  r  r' — ( n — 1)  t  r'  J-  +  t  r  r' 
v  = _ t _ ) - 

u  |  n  (n — 1)  ( r  +  r') — ( n — l)2 1  j-  -f-  (n — 1)  t  r — n  r  r' 

There  t  is  the  thickness  of  the  lens,  r  r'  the  radii,  and  n  the  index  of  refraction. 
— Secretan ,  Systemes  Optiques  Gonvergents ,  54. 


FOCAL  LENGTHS  OF  LENSES. 


77 


else  to  consider  the  various  focal  lengths  as  measured  from  the 
centres  of  admission  and  emission  already  described  (p.  69).  In 
the  case  of  a  plano-convex  lens,  these  centres  fall  together  at  the 
centre  of  the  convex  curve,  and  the  focal  lengths  are  correctly 
measured  from  the  point  C  in  the  figure. 

Although,  exactly  speaking,  the  focal  length  of  the  image 
always  varies  with  its  distance  from  the  lens,  yet  there  is  practi¬ 
cally  a  distance  for  each  lens  beyond  which  all  objects  are  simul¬ 
taneously  in  focus.  If,  for  example,  we  say  that  a  difference  of 
focal  length  not  exceeding  ^  of  an  inch  may  be  neglected,  then 
we  may  fix  for  every  focal  length  of  lens  the  distance  beyond 
which  all  objects  are  practically  at  once  in  focus. 

fu 

We  had  on  the  last  page  the  formula  v  =  — ■  -j,  Now,  if  the 

limit  of  u  is  that  it  shall  not  be  more  than  -g\  of  an  inch  longer 

than  the  principal  focus,  put  u  =  /  +  -  ,  and  we  have 

oo 


V  =  50/2  +  /. 

As  /  is  inconsiderable  in  comparison  with  the  other  members 
of  the  equation,  it  may  practically  be  neglected,  and  it  may  be 
said  that  all  objects  that  are  distant  over  fifty  times  the  square 
of  the  focus,  are  simultaneously  in  focus. 

Consequently : — • 


For  lenses  of 

3 

inches  focal  length  the  distance  is 

37j  feet. 

u 

tt 

6 

u 

tt 

tt  tt 

150  “ 

<( 

(t 

8± 

tt 

tt 

1 1  u 

300  “ 

u 

tt 

10 

tt 

tt 

•  u  u 

417  “ 

u 

tt 

12 

.( 

ti 

tt  tt 

600  “ 

tt 

tt 

16 

tt 

tt 

U  (t 

1065  “ 

Objects  at  these  distances  may  be  said  to  have  practically  the 
same  focal  length  as  those  at  any  greater  distance.  To  get  objects 
at  these  distances  into  focus  simultaneously  with  those  at  less 
distance,  we  must  depend  upon  the  11  depth  of  focus”  of  the  lens,  a 
very  precious  quality  possessed  by  different  lenses  in  very  various 
degrees. 

When  the  image  is  formed  by  rays  which  meet  at  a  very  small 
angle,  as  at  F,  Fig.  87,  it  is  evident  that  the  focussing  screen  can 
be  racked  a  little  in  or  out  without  much  injury  to  the  definition, 
and  thus  a  good  uniform  average  focus  is  obtained. 


78 


GENERAL  OPTICS. 


CHAPTEB  Y. 

PHOTOGRAPHIC  OBJECTIVES. 

In  this  chapter  will  be  briefly  considered  the  various  forms  of 
photographic  objectives  now  chiefly  used. 

§  1. — The  View  Lens. 

By  a  view  lens  is  understood  a  single  achromatic  combination, 
■usually  consisting  of  two  pieces,  forming  a  meniscus  or  a  plano¬ 
convex  lens,  with  the  concave  or  plane  face,  as  the  case  may  be, 
turned  to  the  light.  This  form  of  lens  is  figured  at  page  61,  Figs. 
80,  81,  32.  The  combination  of  a  double  convex  of  crown  and  a 
double  concave  of  flint  glass  is  the  usual  method  employed. 

Latterly  Dallmeyer  has  produced  a  wide  angle  view  lens,  con¬ 
structed  of  three  pieces,  as  shown  in  the  margin  (Fig.  56). 

A  flint  negative  meniscus  is  inclosed  between  two  menisci  of 

crown  glass.  In  these  two  latter 
the  crown  glass  is  not  of  equal 
refractive  power,  the  rear  lens 
having  a  somewhat  less  index  of 
refraction  than  the  front. 

In  this  way  a  most  excellent 
lens  is  formed.  It  has,  of  course, 
the  fault  common  to  all  lenses  not 
centrally  stopped,  that  straight 
lines  are  more  or  less  curved  on 
the  image.  It  is  therefore  only 
suited  for  landscapes  in  which 
architectural  subjects  are  not  in¬ 
serted,  or  where  these  are  small 
and  inconspicuous.  But  for  all 
cases  in  which  it  can  be  properly  used,  and  these  are  very  nume¬ 
rous,  the  writer  thinks  very  highly  of  it.  If  this  lens  be  criti¬ 
cally  compared  with  the  Steinheil  aplanatic,  it  will  be  found  that, 
in  respect  of  that  very  important  quality,  depth  of  focus,  the  wide 
angle  view  lens  has  a  distinct  advantage.  It  also  covers  satisfac- 


Fig.  56. 


F  F.  Flint  negative  meniscus, 
c  c.  Two  positive  menisci  of  crown  glass. 
d.  Diaphragm. 


PHOTOGRAPHIC  OBJECTIVES. 


79 


torily  a  wider  angle.  Thus  the  8J  wide  angle  cpvers  a  6|x 
plate,  whereas  with  the  aplanatic  the  9J-inch  is  required.  It  is 
true  that  the  seven-inch  is  sold  for  this  purpose,  which,  however, 
it  does  not  properly  accomplish.  The  9J-inch  Steinheil  used 
on  a  6  J  x  8£  plate  gives,  of  course,  a  rather  less  angle  of  view 
than  the  8J  view  lens,  but,  on  the  other  hand,  gives  a  better  mar¬ 
ginal  definition  and  straight  lines. 

The  wide  angle  view  lenses  more  than  cover  the  plates  for 
which  they  are  advertised,  and  admit  of  a  little  pushing  up  or 
down  of  the  camera  front,  without  producing  black  corners.  The 
writer  has  not  found  any  more  serviceable  lens  for  view-making. 


§  2. — The  Portrait  Lens. 

The  form  of  objective  represented  at  Fig.  57  is  that  at  the  pre¬ 
sent  time  exclusively  used  for  portraiture.  It  was  the  result  of 

Fig.  57. 


F,  F.  Negative  lliat  lenses ;  the  front,  plano-concave,  the  hack,  negative  meniscus. 

/,/.  Flange 
D.  Diaphragm. 

the  labors  of  Petzval,  of  Vienna,  who  calculated  this  combina¬ 
tion,  and  by  its  immense  improvement  over  the  systems  pre¬ 
viously  in  use  for  portraiture  gave  a  vast  impetus  to  that  branch 
of  photographic  art.  A  glance  at  the  figure  will  at  once  explain 
the  nature  of  the  arrangement. 

As  the  portrait  is  most  natural  and  effective  when  the  sitter 


80 


GENERAL  OPTICS. 


has  not  been  compelled  for  a  length  of  time  to  retain  his  position, 
and  as  the  chances  of  moving  are  greatly  increased  with  the 
length  of  the  exposure,  the  great  object  of  the  portrait  combina¬ 
tion  is  to  throw  as  strong  a  body  of  light  into  the  camera  as 
possible.  Considerations  of  depth  of  focus,  correction  for  sphe¬ 
rical  aberration,  &c.,  have  been  necessarily,  to  some  extent,  sub¬ 
ordinated  to 'the  one  great  need. 

It  follows  that,  instead  of  having  many  planes  in  excellent 
focus  simultaneously,  as  in  the  case  of  the  view  lens,  the  portrait 
lens  is  very  restricted  in  this  respect,  and  hence  cannot  be 
appropriately  used  except  for  the  purpose  for  which  it  is 
intended. 

Some  portrait  lenses,  especially  the  Jamin  (Darlot)  lenses,  are 
arranged  to  permit  of  the  front  portion,  consisting  of  the  double 
convex  and  plano-concave,  to  be  unscrewed,  and  after  reversing, 
be  screwed  into  the  same  flange  for  use  as  a  view  lens.  This  is  a 
very  convenient  system ;  it  is,  however,  liable  to  the  objection 
that  the  front  surface  of  the  view  lens  thus  made  is  plane,  instead 
of  concave.  Now,  to  get  the  best  results,  not  only  the  front  sur¬ 
face  should  be  concave,  but  this  concavity  should  be  consider¬ 
able.  Such  a  view  lens  cannot,  therefore,  be  expected  to  give 
strictly  first-rate  results,  though  it  may  do  good  work.  It  can¬ 
not  be  too  clearly  understood  by  the  student,  that  the  whole 
system  of  photographic  objectives  is  a  system  of  compromises 
between  conflicting  troubles;  that  these  compromises  can  always 
be  best  adjusted  for  some  definite  end,  and  that  consequently 
when  one  sort  ot  objective  is  made  to  do  another’s  work,  such 
work  is  always  done  at  a  disadvantage. 

Mr.  Dallmeyer  gives  the  following  information  relative  to  the 
character  of  portrait  lens  best  suited  for  given  sizes  of  plates, 
supposing  the  camera  to  be  placed  at  a  distance  of  18  to  20  feet 
from  the  sitter,  as  he  advises. 

The  equivalent  focal  length  of  the  lens  for  a  given  sized  plate 
should  be  about  double  its  largest  side ;  that  is  for  card  size, 
4J  x  8 J,  the  focal  length  should  be  8  to  9  inches ;  for  cabinet 
size,  6x5,  12  inches;  for  8x10  plates,  20  inches.  Salomon’s 
success  confirms  these  views;  his  8x10  plates  are  made  with  a 
lens  of  20  inch  focus. 

Next  arises  the  question  as  to  what  diameters  these  lenses 
should  have.  It  is  useless  to  expect  that  the  highest  degrees  of 
rapidity,  flatness  of  field,  and  depth  of  focus  can  be  combined, 


PHOTOGRAPHIC  OBJECTIVES. 


81 


because  these  qualities  are  essentially  antagonistic.  So  that  two 
lenses,  both  perfectly  corrected  for  spherical  aberration,  and  of 
the  same  focus,  the  one  of  two  inches  diameter,  will  have  double 
the  depth  of  focus  of  the  other,  whilst  the  latter,  on  the  other 
hand,  is  four  times  more  rapid. 

Or  again,  comparing  two  lenses,  both  having  the  same  ratio  of 
diameter  to  focal  length,  consequently  of  equal  (or  nearly  equal) 
rapidity,  the  greater  the  length  of  focus  the  less  the  11  depth”  of 
focus.  Thus,  for  example,  a  card  lens  of  9  inches  equivalent 
focus  and  2}  diameter,  producing  a  card  picture  at  20  feet,  will 
sufficiently  define  accessories  at  eighteen  inches  in  front  of,  and 
behind  the  principal  object  having  thus  a  “  depth”  of  3  feet, 
whereas  a  lens  of  twice  the  focal  length  placed  at  the  same  distance 
of  20  feet ,  will  have  but  half  the  “  depth,”  viz.,  9  inches  before 
and  behind  the  object,  but  will  produce  an  image  four  times,  i.e. 
twice  linear,  the  size. 

These  lenses  were  first  manufactured  by  the  well-known  firm 
of  the  Voigtlasnders.  Now  they  are  made  by  opticians  generally. 


§3. — Steinheil’s  “  Aplanatic”  and  Dallmeyer’s  “Rapid  Rectilinear.” 

Several  years  ago  two  lenses  were  invented,  the  one  in  Eng¬ 
land,  the  other  in  Germany,  which  are  remarkable  in  their  per¬ 
formances,  and  in  a  certain  similarity  to  each  other. 


Fig.  58. 


82 


GENERAL  OPTICS. 


Steinheil’s  aplanatic,  of  which  a  figure  is  given  below,  for  which 
the  writer  is  indebted  to  Dr.  Liesegang’s  Archiv ,  has  already 
become  a  great  favorite  in  this  country.  It  is  a  “  symmetrical 
doublet,”  that  is,  the  front  and  back  lenses  are  alike.  Each  con¬ 
sists  wholly  of  flint  glass,  but  the  respective  portions  being  com¬ 
posed  of  flint  glass  of  different  refractive  powers,  correct  each 
other,  so  that  the  lenses  are  achromatized ;  in  this  is  an  essential 
difference  from  any  other  lens  hitherto  constructed. 

It  is  an  advantage  in  the  Steinheil  lens  that  when  used  with  a 
large  diaphragm,  although  the  exterior  portions  of  the  image 
lose  their  sharpness,  the  central  portions  are  still  tolerably  good. 
As  the  rapidity  of  a  lens  increases  greatly  with  the  increase  of 
the  diaphragm,  we  may  thus  employ  the  aplanatic  as  a  portrait 
lens,  if  we  reject  all  but  the  central  portions.  It  does  not,  how¬ 
ever,  in  this  way  attain  the  rapidity  of  a  good  portrait  lens.  For 
groups ,  it  and  the  Dallmeyer  rapid  rectilinear  are  probably  the 
best  of  all  lenses. 

The  Dallmeyer  rapid  rectilinear  greatly  resembles  the  Stein¬ 
heil  aplanatic  in  its  form.  Its  symmetrical  lenses  are  not,  how¬ 
ever,  made  of  flint  glass  only,  but  of  flint  and  crown  achroma¬ 
tized  in  the  usual  manner.  Although  less  known  in  this  country, 
they  are  equal  to  the  Steinheil ;  indeed,  there  is,  as  far  as  the 
writer’s  experience  goes,  no  choice  between  them. 

One  important  point  in  the  comparison  should  be  noted.  Simi¬ 
lar  as  these  lenses  are,  their  makers  have  taken  different  views  as 
to  their  powers,  and  the  Steinheil  lenses  are  advertised  to  cover 
a  plate  one  size  larger  than  the  Dallmeyer.  Thus  the  Steinheil 
having  about  9  inches  focal  length,  is  advertised  for  use  for 
8  x  10  plates,  whilst  the  corresponding  lens  of  Dallmeyer  is 
advertised  for  6 J  x  8 \  plates.  This  might  naturally  lead  to  mis¬ 
conception,  in  the  supposition  that  the  lenses  covered  different 
angles  and  had  different  powers.  The  fact  is  that  the  nine  inch 
lens  will  with  a  little  straining  cover  (in  either  case)  ao  8  x  10 
plate,  and  may  be  used  with  it,  but  generally  will  be  found  best 
suited  for  a  6Jx8J.  In  other  words,  the  nine  inch  focus  lens, 
when  worked  with  a  fair-sized  stop,  has  hardly  power  enough 
for  the  8  x  10,  and  rather  more  than  power  enough  for  the 
6J  x  8J. 

These  lenses  fall  off  a  good  deal  in  illumination  towards  the 
edges.  At  the  centre,  the  definition  cannot-  in  the  writer's  opinion 


PHOTOGRAPHIC  OBJECTIVES. 


83 


be  easily  surpassed,  but  as  we  pass  from  tbe  centre,  it  rapidly 
falls  off,  unless  sharply  stopped  down. 

For  architectural  work  both  these  lenses  have  no  superiors,  and 
the  same  may  be  said  as  to  groups.  They  are  useful  for  instan¬ 
taneous  work,  though  not  so  rapid  as  a  first-class  portrait  lens, 
and  the  same  is  true  of  portraiture.  For  copying  they  are  ex¬ 
cellent.  When  width  of  angle  of  view  is  important,  they  are 
exceeded  by  several  lenses,  by  Zentmayer’s 
lens,  by  Dallmeyer’s  wide-angle  rectilinear,  by  Fig.  59. 

Steinheil’s  pantoscope,  &c. 

SteinheiVs  Uncorrecled  Lens. — Previous  to 
the  discovery  of  the  lens  above  described, 

Prof.  Steinheil  devised  a  lens  consisting  of 
two  uncorrected  menisci,  which  were  remark¬ 
able  for  the  great  size  of  plate  covered  by  so 
small  a  lens.  The  adjoining  figure  gives  an 
idea  of  its  construction.  It  is  now  superseded 
by  his  achromatized  doublet  or  aplanatic. 

A  useful  maxim,  familiar  to  experienced  photographers,  is 
never  to  strain  a  lens.  Some  who  purchase  a  lens  intended  to 
cover  a  given  size  of  plate,  and  who  find  that  by  using  a  very 
small  stop,  good  definition  can  be  got  over  a  materially  larger 
plate  than  that  for  which  the  lens  was  advertised,  think  they 
have  made  a  useful  discovery,  and  perhaps  avail  themselves  of  it 
habitually.  The  work  so  produced  will  never  have  the  boldness, 
atmospheric  effect,  gradation  of  distance,  and  transparency  of 
shadow  given  by  a  lens  used  with  a  larger  opening. 

On  the  other  hand,  it  is  a  mistake  to  use  a  lens  intended  for 
larger  views,  in  taking  small  ones.  Lenses  for  large  views  are 
unavoidably  slower,  and  the  extent  of  angle  included  in  a  small 
view,  taken  by  a  longer  focus  lens,  is  too  small.  An  exception 
to  this  is  when  a  lens,  like  the  triplet,  is  used  for  instantaneous 
effect,  and  where  it  is  worked  with  a  large  stop,  rejecting  all  but 
the  centre  of  the  image. 


§  4.— The  Triplet. 

The  triplet  lens  consists  of  two  large  achromatized  menisci, 
between  which  is  placed  a  small  negative  lens  as  near  as  possible 


84 


GENERAL  OPTICS. 


to  the  diaphragm.  The  length  of  the  focus  is  thereby  increased, 
but  at  the  same  time  marginal  definition  is  obtained. 

The  triplet  is  a  lens  which,  although  possessing  great  merits, 
has  been  somewhat  over-praised.  It  is  a  useful  lens  undoubt- 


Fig.  60. 


C,  C.  Double  convex  crown  glass  lenses. 
F,  F.  Double  concave  flint. 

O'.  Double  concave  crown. 

F’.  Double  convex  flint. 

D.  Diaphragm  with  its  opening  at  F'. 
/,/.  Flange. 


edly,  but  since  critically  examining  its  power,  the  writer  finds 
himself  led  to  the  following  comparison : — 

For  architectural  objects  it  is  surpassed  by  the  Steinheil,  the 
Dallmeyer  rapid  rectilinear,  and  by  Zentmayer’s  lens,  the  last 
mentioned  of  which  gives  lines  equally  straight,  and  includes  a 
very  much  larger  angle.  Where  angle  is  no  object,  where  we 
have  free  open  space  in  the  desired  direction  about  the  archi¬ 
tectural  object,  there  only  the  triplet  may  be  conveniently  em¬ 
ployed. 

For  copying,  it  is  surpassed  by  the  same  lens. 

For  views  not  embracing  architectural  objects,  or  where  these 
are  not  near  the  margin,  and  are  inconspicuous,  it  is  undoubtedly 
surpassed  by  the  view  lens,  especially  by  Dallmeyer’s  wide  angle 
view  lens. 


PHOTOGRAPHIC  OBJECTIVES. 


85 


For  portraiture,  it  is  inferior  to  the  portrait  lens,  being  much 
slower.  By  removing  the  central  negative  lens,  however,  its 
action  is  increased ;  but  the  centre  of  the  image  only  is  sharp 
enough  for  use,  as  in  the  case  of  portraits  to  be  vignetted. 

§  5. — The  Globe  Lens. 

The  globe  form  of  lens  was  devised  in  this  country  by  Mr. 
Schnitzer,  and  was  manufactured  by  him  in  connection  with  the 
late  Mr.  Harrison.  Its  character¬ 
istic  feature  lies  in  this,  that  the 
exterior  curves,  back  and  front, 
form  part  of  one  and  the  same 
sphere,  the  diaphragm  being 
placed  at  the  centre  of  that 
sphere.  Consequently  it  follows 
that  the  incident  ray  R,  Fig.  62, 
which  passes  through  the  centre, 
has  a  nearly  perpendicular  inci¬ 
dence  upon  the  outside  surface. 

It  therefore  undergoes  but  little 
deviation  at  either  of  the  four 
surfaces,  but  necessarily  encoun¬ 
ters  some,  and  is  bent  from  its 
original  direction  R  P  down  to 
D.  A  grave  objection  to  this  lens 
lies  in  its  tendency  to  form  a 


Fig.  62. 


thicker  spot  at  the  centre  of  the  image,  called  flare ,  or  ghost,  the 
cause  of  which  will  be  explained  further  on  (see  p.  91). 


Fig.  61. 


C,  C.  Positive  menisci  of  crown  glass. 
F,  F.  Negative  menisci  of  flint  glass. 

D.  Diaphragm. 

/,  /.  Flange. 


86 


GENERAL  OPTICS. 


§  6. — The  Zentmayer  Lens. 

Mr.  Joseph  Zentmayer,  of  this  city,  has  succeeded  in  making  a 
photographic  objective  of  a  single  sort  of  glass,  his  lenses  being 
both  uncorrected  menisci.  Nevertheless,  in  these  objectives  the 
chemical  and  visual  foci  are  practically  coincident.  This  single 
fact  would  be  enough  to  invest  the  lens  with  interest,  but  its 
performances  are  sufficiently  remarkable  to  indicate  that  this 

lens  will  be  adopted  for  all  those 
descriptions  of  work  to  which  it  is 
especially  suited. 

Fig.  63  will  give  a  clear  idea  of 
the  system  of  construction.  The 
front  and  back  curves  of  each  lens 
stand  to  each  other  in  the  relation 
of  12  to  13,  and  the  two  lenses  to 
each  other  in  the  ratio  of  2  to  3. 
The  stop  is  advanced  a  little  nearer 
to  the  front  lens  than  the  centre  of 
curvature  of  the  exterior  surface  of 
the  larger  lens. 

It  is  evident  that  by  having  a 
series  of  lenses  of  different  sizes,  the 
larger  lens  of  one  pair  may  serve 
as  the  smaller  lens  for  the  next  larger  pair.  On  this  principle 
these  lenses  are  manufactured.  The  complete  sets  embrace  six 
lenses,  capable  of  forming  five  pairs,  having  a  great  range  of 
focal  lengths.  Smaller  sets  are  made,  in  which  four  lenses  form 
three  pairs. 

These  lenses  include  a  wonderful  angle — fully  as  much  as  can 
ever  be  advantageously  used,  and  much  more  than  covered  by 
the  globe  lens.  The  architectural  effects  attained  are  good,  and 
bolder  than  would  be  expected  from  the  small  size  of  the  stop 
that  must  be  used.  The  reflecting  surfaces  which  the  ray  meets 
in  this  lens  are  fewer  than  in  any  other  centrally  stopped  objec¬ 
tive,  and  this  gives  brilliancy  as  well  as  diminishes  the  propor¬ 
tion  of  light  lost.  For  copying  these  lenses  are  at  least  as  good 
as  any.  They  are,  in  the  opinion  of  the  writer,  unsuitable  for 
landscape  work,  by  reason  of  the  small  stop  required. 


Fig.  63. 


PHOTOGRAPHIC  OBJECTIVES. 


87 


§  7  — Ross’s  Doublet. 

Mr.  Eoss’s  form  of  doublet,  Fig. 

64,  has  been  favorably  spoken  of. 

It  is  intended  for  views  and  archi¬ 
tecture,  of  which  last  it  preserves 
the  straight  lines,  and  for  copying. 

A  material  convenience  is  afforded 
with  this  lens,  an  internal  shutter, 
sliding  across  the  opening  of  the 
diaphragm,  instead  of  covering  and 
uncovering  the  lens  in  the  usual 
way  with  a  cap.  This  feature  has 
been  also  introduced  into  Zentmayer’s 
lenses. 

Eoss’s  lenses  may  be  separated, 
and  each  can  be  used  as  a  single 
landscape  lens. 

§  8  — Other  Forms  of  Photographic  Lenses. 

Orthoscopic  Lens. — This  form  which,  like  the  portrait  lens,  we 
owe  to  Petzval,  has  been  extensively  used,  especially  in  this 
country.  Harrison  manufactured  many  good  objectives  of  this 
form  ;  but  on  introducing  the  globe  lens,  he  stopped  making  the 
orthoscopic,  and  this  lens  is  now  but  little  used  here.  In  Ger¬ 
many  it  seems  to  have  kept  its  place  better. 

The  orthoscopic  is  an  excellent  copying  lens,  but  slow,  owing 
to  its  long  focus,  and  the  small  stop  generally  used  with  it  in 
copying.  For  taking  views,  a  stop  of  considerable  size  may  be 
employed ;  and,  as  it  has  a  considerable  depth  of  focus,  it  is  by 
some  much  prized  for  landscape  work;  though  this  is  rather  in 
Germany  than  here.  Small  pictures  of  landscape  scenery  are 
well  taken  by  the  smaller  orthoscopic  lenses,  because  in  them 
the  focal  length  is  not  far  from  corresponding  with  that  of  the 
eye.  But  large  pictures  made  with  the  orthoscopic  require  a  lens 
of  very  long  focus;  and  it  results  that  planes  of  distance  are  not 
well  rendered,  the  foregrounds  become  indistinct  and  inconspic¬ 
uous,  and  distant  objects  look  unnaturally  near.  The  remarkable 
influence  exerted  by  the  focal  length  of  a  lens  upon  the  resulting 
image  will  be  fully  explained  a  few  pages  further  on. 


Fig.  64. 


L,  L.  Positive  menisci,  corrected. 
D.  Diaphragm. 


88 


GENERAL  OPTICS. 


Busch's  Pantoscope  consists  of  two  corrected  lenses  with  a  cen¬ 
tral  stop.  It  includes  a  very  large  angle  of  view,  and  has  been 
highly  spoken  of.  A  very  carefully  constructed  camera  appears 
to  be  necessary  for  it. 

Blunt's  Hemispherical  Lens. — Mr.  Blunt,  of  New  York,  con¬ 
structs  a  lens  of  this  name,  which  is  spoken  of  in  very  high 
terms  by  Mr.  Hull  and  other  competent  judges.  Mr.  Hull  affirms 
it  to  be  equal  to  any  other  lens  for  landscape  purposes,  without 
exception.  It  is  also  suited  for  architecture  and  for  copying, 

Dallmeyer's  Rectilinear.  —  This  lens  is  less  rapid  than  the 
“  Rapid”  and  the  Steinheil  aplanatic,  but  covers  a  very  large 
angle,  about  100°.  It  gives  straight  lines. 

Panoramic  Cameras. — The  theory  of  this  very  ingenious  instru¬ 
ment,  by  which  such  beautiful  results  have  been  obtained,  is  as 
follows  :■ — 

Let  Ybe  the  centre  of  emission  of  the  cone  of  rays  coming  out 

from  any  objective,  single,  double, 
or  triple,  which  finds  its  focus  on 
the  screen  S  S'. 

If  now  the  lens  be  made  to  rotate 
horizontally,  on  J  as  a  centre ,  the 
position  of  objects  in  the  image 
formed  on  the  focussing  screen  will 
not  change.  If  the  image  of  any  ex¬ 
terior  object,  for  example,  falls  at 
the  centre  F,  the  rotation  of  the  lens 
will  not  cause  the  image  of  that 
body  to  move,  but  it  will  remain  accurately  at  F  until  the  lens 
rotates  so  much  that  it  passes  out  of  the  field  of  view. 

Now,  to  avail  ourselves  of  this  property,  we  must  remember 
that  when  the  lens  is  rotated  so  that  its  axis  passes  from  the  di¬ 
rection  J  A  to  the  direction  J  A',  its  image  is  no  longer  in  focus 
on  the  screen  at  A',  but  at  the  point  F' ;  because  the  central  ray 
is  now  in  the  direction  J  A,  and  its  focal  length  will  be  the  same 
it  originally  was,  viz.,  J F  or  J F'. 

The  first  idea  for  applying  these  principles  would  evidently  be 
to  use  a  sensitive  plate  of  a  cylindrical  form,  corresponding  with 
the  curve  F"  F  F\  and  by  means  of  a  mask  with  a  vertical  slit, 
to  conceal  all  the  plate  but  a  high  narrow  strip  at  the  centre  ; 
then  if  the  plate  F"  F F'  remained  stationary,  and  the  lens  rotated 


Fig.  65. 


PHOTOGRAPHIC  OBJECTIVES. 


89 


carrying  the  mask  with  it,  every  part  of  the  plate  would  he  ex¬ 
posed  successively. 

But  in  the  instrument  now  in  use,  this  is  otherwise  managed. 
The  sensitive  plate  occupies  the  position  S  S',  and  is  flat.  It  is 
masked,  with  a  narrow  opening  at  F,  extending  from  top  to  bottom. 
As  the  lens  rotates,  the  plate  S  S'  is  shifted  sideways  by  a  system 
of  clockwork,  which  makes  its  movement  exactly  correspond 
with  that  of  the  lens,  whether  it  be  slow  or  fast,  as  the  light  may 
require. 

As  a  curved  plate,  F'  F  F"  would  receive  a  perfect  image  from 
the  rotating  lens,  masked  as  above  explained,  all  that  is  necessary 
is  that  the  flat  plate  S S'  should  be  shifted  in  such  a  way  that 
when,  for  instance,  the  lens  has  moved  so  that  its  axis  is  in  the 
direction  J F' ,  then  the  plate  shall  have  been  brought  up  to  F' , 
there  to  receive  its  image  at  its  correct  focus.  And,  evidently, 
if  the  plate  be  long  enough,  and  the  camera  be  rotated  to  a  full 
circle,  an  entire  panorama  may  be  obtained. 

This  picture  will  be  found  to  differ  materially  from  one  obtained 
in  the  ordinary  camera.  It  will  be  in  panoramic,  instead  of  plane 
projection.  The  picture  will  not  be  an  harmonious  whole,  which 
the  eye  sees  whilst  regarding  its  perspective  centre,  but  as  if  the 
eye  were  directed  always  opposite  to  it,  in  whatever  direction  it 
chanced  to  look,  or,  to  speak  more  exactly,  as  if  the  eyes  were 
directed  in  succession  at  all  the  vertical  lines  in  the  picture. 

Another  difference  will  be,  that  from  end  to  end  (but  not  from 
top  to  bottom)  the  picture,  no  matter  how  large,  will  be  in  equally 
good  focus.  At  the  right  and  left  extremities  the  picture  will 
be  as  sharp  as  the  middle.  This  is  because  the  central  part  of 
the  image  only  is  used.  Each  part  becomes  successively  the 
centre. 

Again,  the  vertical  slit  at  F  may  be  made  narrow  at  bottom 
and  wide  at  top,  so  that  the  foreground  will  get  a  larger  exposure 
than  the  sky  ;  and  this  difference  may  be  regulated  at  will,  giving, 
if  desired,  to  the  sky  an  exposure  of  one-tenth  or  less  than  that 
which  the  foreground  receives.  It  is  this  which  has  enabled 
Braun  to  produce  such  wonderful  cloud  pictures  in  his  Swiss 
scenery,  and  t6  get  good  definition  of  snow  mountains  against 
the  sky  and  clouds. 

The  most  successful  application  of  this  principle  is  at  present 
Johnson’s  panoramic  camera.  It  is  patented,  but  the  patent  can¬ 
not  cover  the  principle,  which  was  understood  many  years  before 

7 


90 


GENERAL  OPTICS. 


his  application  of  it,  and  was  applied  to  the  construction  of  pano¬ 
ramic  cameras.1 


§  9. — General  Remarks  on  Lenses. 

Portraiture. — The  portrait  lens  is  so  far  superior  to  all  others 
for  this  purpose  that  none  other  is  habitually  used.  The  Stein  - 
heil  aplanatic  is  the  form  that  comes  nearest  in  efficiency ;  it  is 
now  occasionally  used  for  portraits,  and  is  probably  unsurpassed 
for  taking  groups. 

For  card  portraits  the  focal  length  needed  for  the  lens  will 
depend  upon  how  much  is  to  be  included.  For  full  lengths,  very 
short  focus  lenses  are  commonly  employed.  For  such  as  show 
part  of  the  body,  and  even  including  the  hands,  lenses  of  six  to 
eight  or  nine  inches  focal  length  will  be  proper.  For  “cabinet 
size”  lenses  of  eight  to  twelve  inches  focal  length  will  be  needed. 
For  6}x  8J  plates  and  half-length  portraits,  a  lens  of  from  ten  to 
sixteen  inches  will  be  suitable.  For  very  short  exposures,  espe¬ 
cially  in  taking  children,  “  extra  rapid”  lenses  are  made,  -with 
very  short  focal  lengths.  Some  makers  make  a  difference  in  their 
lenses  according  as  they  are  wanted  for  full  lengths  and  for  vig¬ 
netted  heads.  In  the  latter  case  every  effort  is  made  for  perfect 
definition  at  the  centre;  in  the  former  a  good  definition  all  over 
the  plate  is  aimed  at. 

Generally,  the  shorter  the  focal  length,  the  less  exposure  will 
V  be  needed,  and  the  facility  of  getting  all  portions  of  the  image 

into  focus  will  be  greater ;  but  the  longer  the  focal  length,  the 
less  exaggeration  there  will  be  in  those  parts  that  project,  the 
hands  especially. 

Very  ingenious  arrangements  have  been  adapted  to  the  portrait 
lens,  with  the  object  of  changing  the  focus  during  exposure,  in 
the  effort  to  get  a  diffusion  of  focus,  and,  instead  of  having  one 
part  sharp  to  the  exclusion  of  the  rest,  to  maintain  a  certain 
average  of  sharpness  over  the  whole.  Even  lenses  have  been 
made  in  which  a  certain  amount  of  spherical  aberration  has  been 
left  uncorrected,  in  order  to  diffuse  the  sharpness.  The  late  Mr. 
Claudet  brought  this  whole  matter  prominently  forward  shortly 
before  his  death,  and  opinions  are  very  much  divided  on  the 
subject. 

1  See  Secretan ,  Be  la  distance  focale  des  Systemes  Optiques  Conner gents.  Paris, 
1855. 


PHOTOGRAPHIC  OBJECTIVES. 


91 


Landscapes. — As  already  said,  for  such  cases  where  it  is  appli¬ 
cable,  the  single  view  lens,  especially  the  wide-angle  form,  is 
exceedingly  satisfactory.  The  small  angle  included  by  the  com¬ 
mon  view  lens  is  often  a  great  objection.  The  rapid  rectilinear 
of  Dallmeyer,  and  the  aplanatic  of  Steinheil,  are  exceedingly  use¬ 
ful  in  landscape  work,  are  quick,  clean,  free  from  flare,  and  cover 
a  very  satisfactory  and  sufficient  angle.  Between  the  two  there 
is  little  choice.  In  using  the  aplanatic,  the  photographer  is  advised 
to  employ  a  lens  of  one  size  larger  than  that  advertised  for  the 
size  of  plate  which  he  has  in  view.  With  the  other  this  is  not 
necessary. 

There  seems  to  exist  a  curious  distinction  between  the  effects 
of  these  forms  of  lenses  which  has  been  little  noticed.  The  wide 
angle  view  lens  produces  a  remarkable  amount  of  detail — every 
stone  in  a  wall,  every  pebble  on  a  shore,  seem  individually 
brought  out,  distinct  from  the  rest.  The  aplanatic  gives  less  of 
this  individualization,  but  perhaps  more  general  harmony.  These 
effects  have  nothing  to  do  with  the  sharpness  of  the  image,  for 
the  distinction  exists  with  lenses  of  equal  focal  length,  equally 
stopped  down,  and  producing  equally  sharp  definition.  If  any 
difference  exists,  the  image  of  the  aplanatic  is  the  sharper  of  the 
two,  at  the  centre.  In  depth  of  focus  the  view  lens  has  the  ad¬ 
vantage. 

Flare  or  ghost  in  the  camera  is  an  indistinct  image  of  the  dia¬ 
phragm.  Let  G  be  the  centre  of  curvature  of  the  second  surface 


of  the  lens,  whose  thickness  is  here  intentionally  exaggerated,  in 
order  to  make  the  lines  visibly  distinct.  A  ray  B1  passing  through 
the  diaphragm,  strikes  the  first  surface,  is  refracted,  and  passes 
to  the  second  at  A.  Here  it  is  divided — most  passing  onwards  in 
a  direction  Rf  to  form  the  true  image,  but  a  part  suffering  reflec¬ 
tion  and  returning  to  the  first  surface.  Here  most  is  transmitted, 
but  a  part  is  reflected  again  and  returns  to  the  second  surface. 
Here  again  the  greater  part  is  transmitted,  after  passing  three 


92 


SPECIAL  OPTICS. 


times  through  the  thickness  of  the  lens,  and,  undergoing  refrac¬ 
tion,  is  bent  down  to  the  axis  at  some  point  F',  producing  the 
flare. 

Comparing  Lenses. — A  great  deal  of  unintentional  injustice  is 
done  by  photographers  in  comparing  lenses,  for  want  of  taking 
the  necessary  precautions  to  make  the  test  a  just  one. 

It  should  invariably  be  borne  in  mind  that  the  performance  of 
a  lens  depends  entirely  upon  its  stopping  down.  Of  two  lenses  com¬ 
pared,  the  inferior  one  may  easily  be  made  to  seem  the  better,  if 
it  be  used  with  a  smaller  stop,  and  no  account  be  taken  of  the 
time  of  exposure. 

It  may  be  taken  for  granted  that  the  sharpness,  depth  of  focus, 
and  size  of  good  picture  obtained  will  always  increase  as  the  size 
of  the  stop  is  diminished.  This  has  led  many  landscapists  to  the 
use  of  extremely  small  stops  habitually,  esteeming  it  of  little 
consequence  to  wait  longer  for  the  impression  to  be  made.  Several 
evils  result  from  this  practice. 

1.  It  may  be  taken  as  an  invariable  rule  that  the  larger  the 
stop  used,  the  more  detail  in  the  shadows  will  be  obtained,  always 
supposing  that  each  trial  has  been  made  with  a  correctly  timed 
exposure.  Let  us  say  that,  with  a  half-inch  stop,  fifteen  seconds 
have  been  found  exactly  right.  Now,  using  a  quarter-inch  stop, 
we  must  expose  for  one  minute  or  rather  more.1  The  exposure 
will  be  correct ;  the  picture  will  be  the  best  obtainable  with  that 
size  of  stop,  but  the  detail  in  the  shadows  will  not  be  so  good  as 
in  the  former  case. 

2.  A  large  stop  gives  a  bolder  picture  and  spaces  it  out  better. 
The  planes  of  distance  are  better  made  out.  A  small  stop  tends 
to  produce  a  map-like  effect.  One-thirtieth  of  an  inch  is  about 
the  limit  for  the  diameter  of  the  stop  for  landscape  work,  and 
one  twenty-fifth  is  much  better,  and  ought  to  be  generally  used. 
That  is,  if  the  lens  have  a  10-inch  focus,  the  stop  should  not  be 
less  than  f  inch,  or  at  farthest  not  less  than  J  inch.  A  small  stop 
tends  to  produce  pictures  destitute  of  atmosphere,  the  distant 
objects  look  too  near. 

3.  A  long  exposure  in  the  case  of  portraiture  is  a  serious  evil. 
Even  with  landscapes  it  is  not  unimportant,  for,  although  the 

1  Theoretically  the  exposure  should  always  be  inversely  proportioned  to  the 
area  of  the  stop,  and  this  area  is  proportional  to  the  square  of  the  diameter  of 
the  stop.  But  in  practice,  it  is  found  that  the  increase  of  exposure  must  be 
considerably  more  than  in  this  proportion. 


PHOTOGRAPHIC  OBJECTIVES. 


93 


contrary  has  been  affirmed,  the  difficulty  of  catching  foliage  still 
always  increases  with  the  length  of  the  exposure. 

The  comparison,  therefore,  between  lenses  of  equal  focal  length 
must  always  be  made  with  stops  of  equal  opening.  Between 
lenses  of  different  focal  lengths  no  true  or  just  comparison  can 
be  made  at  all.  Some  approximation  may  be  reached  by  trying 
them  with  stops  whose  diameter  is  exactly  proportionate  to  the 
focal  length,  but  even  then,  the  smaller  lens  will  always  work 
the  quickest  and  otherwise  appear  to  be  the  best.  The  truth  is 
that  the  difficulties  both  of  the  optician  in  making,  and  of  the 
photographer  in  using,  increase  so  rapidly  with  the  size  of  the 
picture,  that  between  different  sizes  a  just  comparison  is  all  but 
impossible.  A  photographer  who  has  for  a  long  time  worked 
with  any  one  size  of  plate,  and  then  changes  to  a  larger  size  and 
corresponding  lens,  becomes  at  once  aware  of  the  increased  dif¬ 
ficulties  in  his  way.  He  must  exclude  more  foreground,  or  he 
cannot  get  his  whole  picture  well  in  focus.  He  must  use  a  smaller 
stop  also  to  the  same  end.  His  image  on  the  ground  glass  is  not 
nearly  so  brilliant,  and  his  exposures  must  be  materially  pro¬ 
longed  to  get  a  harmonious  negative. 

Selection  of  Lenses. — The  color  of  a  lens  is  always  important. 
Place  the  lens  on  a  perfectly  white  sheet  of  paper — any  brown¬ 
ness  of  tint  is  a  serious  objection.  In  an  old  lens  this  may  arise 
from  the  Canada  Balsam,  with  which  the  separate  portions  are 
cemented  together,  turning  yellow.  If  this  be  thought  to  be  the 
case,  the  lens  should  be  taken  to  an  optician  to  be  separated, 
cleaned,  and  re-attached.  The  photographer  is  not  advised  to 
attempt  this  himself. 

Bubbles  in  the  glass  are  objectionable,  because  they  tend  to 
throw  rays  in  abnormal  directions,  and  to  impair  the  brilliancy 
of  the  image.  One  or  two  small  ones  are  not  important,  nor  a 
sufficient  cause  for  rejecting  an  otherwise  satisfactory  lens.  But 
it  indicates  carelessness  in  the  maker,  as  these  bubbles  are  always 
visible  in  the  disk  from  which  the  lens  is  made,  and  such  disks 
should  be  rejected. 

Stride ,  hair-like  or  thready  transparent  lines,  are  very  objec¬ 
tionable,  and  at  once  a  sufficient  cause  for  rejection. 

Scratches. — Lenses  will  sometimes  come  from  the  maker  with 
scratches,  the  result  of  careless  handling  of  tools  in  setting,  or 
of  bad  packing.  Such  of  course  are  returned. 

Centering. — To  every  lens  there  belongs  an  optical  axis,  a  line 


94 


SPECIAL  OPTICS. 


perpendicular  to  the  surface  of  the  lens,  and  passing  through  its 
centre  of  curvature.  Every  achromatized  lens  consists  of  at 
least  two  portions,  and  it  is  necessary  that  these  should  be  so 
arranged  when  attached  together  by  the  balsam  used  for  that 
purpose,  that  the  optical  axis  of  each  should  exactly  correspond. 
When  two  lenses  or  more  are  united  -to  form  an  objective,  not 
only  must  the  parts  of  each  be  properly  disposed,  but  the  front 
lens  must  have  its  axis  coincident  with  that  of  the  back  lens. 
This  will  depend  upon  correct  mounting. 

The  usual  way  in  which  opticians  test  the  correctness  of  the 
centering,  is  by  making  the  tube  containing  the  lenses  revolve  in 
an  upright  position,  that  is,  with  the  lenses  horizontal.  If,  now, 
a  candle  be  placed  at  a  little  distance,  and  the  eye  be  placed  at  a 
convenient  position,  the  candle  will  be  seen  reflected  from  the 
surface  as  a  bright  point.  Every  surface  of  every  piece  of  glass 
in  the  tube  will  send  back  a  reflection.  Next  the  tube  is  caused 
to  rotate.  Each  lens  that  is  correctly  centered  will  continue  to 
send  its  reflection  back  perfectly  fixed  and  immovable;  but  any 
surface  that  is  out  of  centre  will  cause  its  reflection  to  deviate 
more  or  less,  according  to  the  amount  of  error.  It  is  evidently 
not  necessary  that  all  the  reflections  should  be  seen  at  once,  but 
they  may  be  observed  successively.  This  method  of  observing 
evidently  renders  it  easy  to  fix  which,  if  any,  of  the  surfaces  is 
erroneously  placed,  and  in  which  direction  is  its  error. 

Another  mode  of  observation  is  more  convenient  for  the  pho¬ 
tographer,  as  not  requiring  the  apparatus  needed  for  the  method 
just  described. 

The  observer  places  himself  in  a  dark  room  with  a  single  can¬ 
dle.  Standing  five  or  six  feet  from  it,  he  looks  at  it  through  the 
objective,  inclining  the  latter  a  little  until  he  sees  a  series  of 
bright  points,  which  are  the  images  of  the  candle,  produced  by 
successive  reflections  from  the  different  surfaces  of  the  lens. 
When  a  lens  has  four  pieces  of  glass  in  its  construction,  as  in  the 
case  of  the  portrait,  globe,  orthoscopic,  and  some  other  lenses, 
the  number  of  possible  images  is  very  considerable.  These  can¬ 
not  generally  be  all  found  at  once,  but  eight,  ten,  or  more  can  be 
counted;  a  little  practice,  and  altering  the  inclination  of  the  lens 
materially  aids  in  increasing  the  number. 

If  now  the  centering  is  perfect,  it  will  be  found  that,  by  care¬ 
fully  adjusting  the  position  of  the  lens,  all  of  these  reflections 
can  be  made  to  range  themselves  in  a  straight  line.  But  if  any 


PHOTOGRAPHIC  OBJECTIVES. 


95 


one  or  more  of  the  component  parts  is  out  of  centre,  this  will  be 
found  impracticable.  One  or  more  of  the  bright  points  will  re¬ 
main  obstinately  out  of  line ;  and,  when  a  little  movement  is 
made  which  brings  them  in,  it  will  be  found  that  some  other 
image,  previously  in  line,  has  slid  out  of. it.  When  the  observer, 
after  very  careful  trial,  finds  that  it  is  positively  impossible  to 
make  all  the  images  range,  he  will  be  justified  in  concluding  that 
there  is  a  fault  in  the  centering. 

Whilst  this  test  is  so  easy  that  any  intelligent  observer  can 
apply  it  at  once,  there  is  no  doubt  that  it  is  a  very  severe  one. 
A  lens  may  perform  quite  fairly,  and  yet  such  an  examination  as 
this  may  reveal  a  defect.  But  there  is  no  doubt  that  first-rate 
excellence  is  incompatible  with  such  defectiveness. 

It  is  also  evident  that  the  fewer  the  pieces  of  which  a  lens  is 
composed,  the  less  difficulty  the  optician  will  find  in  getting  them 
all  in  correct  line. 

Quickness. — When  lenses  of  equal  focal  lengths  are  tested 
with  equal  stops,  their  comparative  quickness  will  depend  upon 
the  whiteness  of  the  glass,  the  fewer  number  of  surfaces  that 
enter  into  their  formation,  and  on  the  curves  given  by  the  op¬ 
tician  :  careful  testing,  and  this  alone,  can  settle  the  point. 

Chemical  Focus. — The  correction  for  chromatic  aberration  is  now 
greatly  better  made  than  formerly.  To  test  whether  a  lens  is 
properly  corrected,  select  a  newspaper  printed  with  sharp-cut 
type,  and  paste  a  piece  a  foot  or  fifteen  inches  square  upon  a 
smooth  piece  of  board.  Set  this  up  before  the  camera,  with  the 
columns  vertical,  but  inclined  in  a  slanting  direction,  so  that  one 
side,  the  right,  for  example,  shall  be  a  couple  of  inches  nearer 
the  camera  than  the  left,  keeping  the  board,  however,  exactly  up¬ 
right.  Focus  carefully  along  the  central  upright  line,  and  copy 
it  full  size,  or  thereabouts. 

Next  examine  the  hair-strokes  of  the  letters  on  the  negative 
with  a  microscope.  If  the  lens  is  properly  corrected,  the  central 
line  should  be  in  the  sharpest  focus.  If,  however,  it  be  found 
that  a  portion  to  the  right  or  left  of  the  central  line  is  in  better 
focus  than  the  centre,  then  the  correction  has  evidently  been 
faulty.  If  the  sharpest  image  is  of  a  part  nearer  to  the  lens  than 
the  centre,  the  lens  is  under -corrected ;  if  of  a  part  further  from 
the  centre,  the  lens  is  over-corrected.  In  either  case,  it  is  said  to 
have  a  “  chemical  focus"  that  is,  its  chemical  and  visual  focus 


96 


SPECIAL  OPTICS. 


does  not  correspond,  a  fault  of  the  first  magnitude,  and  sufficient 
cause  for  rejecting  the  lens  entirely. 

Flanges. — The  flange  is  the  brass  circle,  which  is  permanently 
attached  to  the  camera  front,  and  into  which  the  lenses  screw. 
It  is  greatly  to  be  desired  that  opticians  should  adopt  a  regular 
set  of  sizes  and  threads  for  flanges,  so  that  all  the  lenses  habit¬ 
ually  used  with  one  camera  should  screw  into  one  flange,  and 
thus  one  camera  front  only  be  necessary.  This  has  long  been 
done  in  the  case  of  microscopic  objectives,  which,  no  matter 
where  made,  screw  at  once  into  any  instrument,  though  the 
latter  have  been  made  thousands  of  miles  away.  A  similar 
system  is  greatly  needed  in  photographic  objectives.  Dallmeyer 
has  made  some  approximation  to  it,  his  lenses  of  different  sorts 
all  screw  into  the  same  flange,  except  where  the  lenses  are  of 
widely  different  focal  length.  But  a  universal  adoption  of  this 
system  is  what  is  wanted. 

§  10. — Care  of  Lenses. 

A  few  words  on  the  preservation  and  care  of  these  beautiful 
products  of  science  and  art  will  not  be  inappropriate  here. 

When  lenses  have  been  out  of  use  for  some  time,  or  have  been 
carried  to  a  distance,  they  should  be  carefully  unscrewed  and 
wiped  out  with  a  soft  old  linen  handkerchief,  or  a  piece  of  chamois 
leather.  Nothing  else  should  be  used. 

If  the  lenses  have  stood  only  for  a  short  time,  they  may  only 
require  wiping  on  the  exterior  surfaces.  They  should  first  be 
examined,  and  if  free  from  dust,  it  is  better  not  to  wipe  them. 
Toojnuch  wiping  is  as  bad  as  too  little,  and  it  may  be  set  down 
as  a  general  principle,  that  the  less  lenses  are  touched  with  any¬ 
thing  the  better  ;  especially  the  fingers  should  never  touch  them. 

With  many  forms  of  lenses,  convenient  caps  of  morocco  lined 
with  velvet  are  now  furnished.  This  is  an  excellent  arrange¬ 
ment,  as  dust  is  excluded,  and  the  amount  of  wiping  is  diminished. 
These  caps  are  also  very  convenient  for  covering  and  uncovering 
the  lens.  Such  should  be  made  and  furnished  with  all  photo¬ 
graphic  objectives.  Something  similar,  or  a  light  brass  cap,  to 
protect  the  back  lens,  would  also  be  very  useful  with  all  lenses 
intended  for  field  use. 

It  is  a  disadvantage  to  keep  the  lens  in  a  cold  place,  and  then? 
perhaps,  suddenly  remove  it  to  a  warm  one.  A  dew  may  form 


PHOTOGRAPHIC  PERSPECTIVE. 


97 


on  the  lens  while  the  image  is  being  impressed,  or  before,  and 
may  escape  observation.  This  may  even  happen  by  a  mere 
change  of  position  in  taking  views,  by  the  photographer  remov¬ 
ing  his  apparatus  from  a  cool  position  to  a  warmer  and  damper 
one. 

Lenses  should  never  be  left  lying  where  the  sun,  or  even  a 
bright  light,  can  fall  upon  them,  as  strong  light  has  a  tendency 
to  darken  the  color  of  the  glass  and  increase  the  exposure  ne¬ 
cessary.  For  this  reason,  where  steoroscopic  lenses  are  occasion¬ 
ally  used  separately,  this  use  should  be  divided  between  the  two. 
If  one  of  the  pair  is  always  used  on  such  occasions,  it  will  tend 
gradually  to  work  more  slowly  than  the  other,  so  that  the  two 
can  no  longer  be  used  advantageously  together. 

The  care  of  the  lens  should  also  be  extended  to  the  brass 
mounting.  If  this  is  allowed  to  become  dented,  or  is  in  any  way 
roughly  treated,  there  is  danger  that  the  centering  may  be  inter¬ 
fered  with,  and  the  working  of  the  objective  thereby  impaired. 
Second-hand  objectives  should  always  be  severely  tested  before 
purchasing,  and  no  one  should  be  induced  to  acquire  a  lens  in 
this  way,  unless  he  feels  fully  capable  of  judging  the  objective  on 
its  own  merits  by  a  careful  trial. 


CHAPTER  VI. 

PHOTOGRAPHIC  PERSPECTIVE. 

\  1. — Nature  of  the  Image  formed  by  a  Lens. 

When  it  was  first  found  that  the  image  of  the  camera  could 
be  fixed,  and  that  thus  representations  of  natural  objects  could 
be  produced  with  critical  exactness,  the  enthusiasm  that  resulted 
was  unbounded.  Gradually  this  was  mixed  with  severe  disap¬ 
pointment.  The  representations  produced  were,  for  the  most 
part,  destitute  of  beauty  even  where  the  subjects  themselves 
were  very  beautiful.  Everything  was  present  in  the  picture,  the 
delineations  were  correct,  or  nearly  so,  and  yet  the  result  was 
most  unsatisfactory. 

It  soon  appeared  that  good  apparatus  and  a  competent  know¬ 
ledge  of  the  process  constituted  only  a  very  small  part  of  what 


98 


SPECIAL  OPTICS. 


was  needed  for  obtaining  a  pleasing  picture.  A  natural  sense  of 
the  beautiful,  and  a  sufficient  acquaintance  with  the  rules  of  art, 
proved  to  be  at  least  equally  necessary.  Without  these  last,  the 
best  point  of  view  at  which  to  place  the  camera  could  not  be 
selected,  the  time  of  day  for  securing  the  best  aspects  of  light 
and  shadow  could  not  be  known,  nor  how  much  to  include  on 
the  plate,  nor  where  to  place  the  horizon  line,  &c.  &c.  The  more 
intelligent  photographers  gave  earnest  attention  to  these  points, 
and  in  proportion  as  they  mastered  them,  their  works  found 
favor.  Those  who  disregarded  them  quickly  sunk  out  of  sight. 

Even  the  nature  of  the  image  formed  by  a  lens  cannot  be  well 
understood  without  some  knowledge  of  perspective.  It  will  well 
repay  any  earnest  landscape  photographer  to  study  this  science 
in  the  text-books  specially  devoted  to  it.  Here,  the  limit  assigned 
by  the  author  to  this  manual  will  permit  of  a  very  brief  descrip¬ 
tion  only. 

Perspective  is  the  science  of  representing  solid  objects  upon 
a  flat  surface. 

If  between  the  object  to  be  represented  and  the  eye,  we  inter¬ 
pose  a  plate  of  glass,  and  keeping  the  eye  steadily  fixed  in  position, 
we  draw  lines  upon  the  glass  corresponding  with  the  objects,  we 
shall  obtain  a  representation  of  these  objects  in  correct  per¬ 
spective. 

Let  us  select  a  building  for  example,  and  on  the  plate  of  glass 
mark  the  point  at  wrhich  we  see  all  the  corners  and  intersections 
of  the  lines  of  the  building.  Then  connecting  these  by  drawing 
lines  on  the  plate  we  shall  obtain  a  representation  such  that  when 
held  up  in  its  proper  position  between  the  eye  and  the  building, 
every  line  on  the  glass  shall  cover  the  corresponding  line  of  the 
building.  This  will  be  one  drawing  of  the  building  in  correct 
perspective. 

But  we  shall  immediately  notice  that  if  we  change  in  the  least 
the  distance  of  the  eye  from  the  plate,  the  correspondence  of  lines 
instantly  ceases.  Still  keeping  the  eye  exactly  opposite  the 
centre  of  the  pane,  let  us  draw  back,  so  as  to  be  farther  from  the 
window ;  at  once  every  line  of  the  building  has  started  out , 
beyond  the  corresponding  line  of  the  original  drawing,  and  we 
obtain  a  larger  picture  than  before. 

By  altering  the  position  of  the  eye,  any  number  of  different 
pictures  will  be  obtained  of  the  same  object,  and  these  correspond 


PHOTOGRAPHIC  PERSPECTIVE. 


99 


with  the  pictures  obtained  from  lenses  whose  absolute  focal  lengths  are 
equal  to  the  distance  of  the  eye ,  in  each  case,fro7n  the  pane  of  glass. 

If  the  arrow  A  B ,  Fig.  67,  represent  the  edifice,  Pf  Pr  the  pane 


of  glass,  and  E  the  eye,  the  edifice  as  represented  on  the  pane 
will  have  the  height  P  P.  If  the  eye  be  withdrawn  to  j B",  the 
image  will  be  enlarged  to  P'  P'. 

Now,  if  the  eye  be  replaced  by  a  lens  whose  focal  length  is 
the  same  as  the  distance  of  the  eye  from  the  pane,  the  image 
formed  by  that  lens  will  be  precisely  the  same  as  seen  by  the 
eye — reversed,  of  course. 

The  lens  L  forms  on  the  screen  an  image  If  (Fig.  68)  of  the 
arrow  precisely  as  large  as  the  image  I  seen  by  the  eye  when 
placed  at  L ,  upon  the  pane  at  Z,  the 
distance  of  the  eye  to  the  pane  being 
the  same  as  the  focal  length  of  the 
lens ;  that  is,  the  distance  from  L  to 
the  centre  of  the  arrow. 

If  now,  keeping  the  eye  at  Z,  we 
move  the  plane  Z,  backwards  and  for¬ 
wards,  we  shall  obtain  any  number  of 
images  of  the  object  A  B.  By  drawing  lines  from  Z  to  all  parts 
of  A  B)  it  will  be  seen  that  the  triangles  are  always  similar;  that 
is,  any  triangle  E  A  B  (Fig.  67)  will  always  be  similar  to  the 
corresponding  triangle  E  P  P.  All  parts  of  the  image  P  P  will 
therefore  have  the  same  proportion  to  the  corresponding  parts  of 
the  object  A  B.  If  any  one  dimension  be  altered,  or  if  P  P  be 
increased  to  Pr  P'  by  drawing  back  the  eye  to  E\  all  others  will 
be  proportionately  changed.  It  follows,  therefore  (and  this  is 
very  important),  that  all  these  images  of  the  object  will  vary  in 
size  only ;  that  is,  they  will  be  magnified  or  reduced  images  of 
each  other ;  and  as  these  images  are  identical  with  those  formed 


Fig.  68. 


100 


SPECIAL  OPTICS. 


by  lenses  placed  at  L  (Fig.  68),  baying  focal  lengths  respectively 
equal  to  any  distance  from  the  eye  to  the  pane,  we  draw  the 
conclusion  that  similar  lenses  of  different  focal  lengths ,  placed  at 
the  same  spot,  give  representations  which  differ  from  each  other  in 
size  only.  If  the  picture  given  by  a  small  lens  be  magnified  (for 
example,  in  a  solar  camera)  to  the  size  of  the  picture  given  by  a 
large  lens,  the  resulting  picture  will  be  identical  with  it,  sup¬ 
posing  the  lenses  to  be  perfect  instruments.  The  perspective 
angles  will  be  the  same.  But  this  is  only  true  when  the  lenses 
have  been  placed  all  successively  on  the  same  spot. 

On  the  other  hand,  changing  the  position  of  the  lens,  or  of  the 
eye,  makes  a  complete  difference  in  the  nature  of  the  image 
formed.  If  A  B  0  D  be  the  side  of  a  house  seen  obliquely,  the 

top  and  bottom  lines,  if  continued, 
will  meet  at  a  vanishing  point  V, 
and  the  perspective  angle  B  V A 
will  be  greater  or  smaller,  ac¬ 
cording  as  we  place  ourselves 
nearer  to  or  farther  from  the 
building.  The  nearer  we  ap¬ 
proach,  the  nearer  the  point  V 
comes  in,  and  the  more  abruptly  the  apparent  size  diminishes 
from  A  B  to  CD.  As  any  good  photographic  lens  placed  in  the 
same  position  as  the  eye  gives  the  same  result,  it  follows  that  the 
nearer  we  go  with  our  lens  to  the  edifice,  the  sharper  will  be  the 
perspective  angle  at  B. 

As  the  influence  of  these  two  conditions,  viz.,  the  focal  lengths 
of  lenses,  and  the  distance  at  which  they  are  removed  from  the 


Fig.  69. 


objects  should  be  very  clearly  understood,  the  writer  has  endea¬ 
vored  to  further  illustrate  it  by  the  accompanying  diagrams. 
Fig.  70  he  has  drawn  in  exact  proportion,  so  that  it  exemplifies 
exactly,  and  not  merely  approximately,  the  mode  of  rendering 


PHOTOGRAPHIC  PERSPECTIVE. 


101 


of  two  given  objects  by  each  of  two  lenses  of  very  different  focal 
lengths. 

Let  us  imagine  two  trees  of  equal  height  standing  the  one 
somewhat  farther  than  the  other,  and  considerably  to  one  side. 
Let  us  assign  to  both  the  height  of  50  feet,  and  let  us  first  place 
our  camera  so  that  the  nearer  tree  is  distant  600  feet.  Let  us 
first  take  a  lens  of  twelve  inches  focus.  The  tree  will  have  the 
exact  height  A  B,  or  one  inch,  upon  the  ground  glass. 

Let  us  now  suppose  that  the  second  tree  is  distant  1000  feet, 
or  400  more  than  the  first.1  Its  image  on  the  ground  glass  will 
measure  six-tenths  of  an  inch  in  height,  and  it  will  occupy  the 
precise  position  C  D,  as  shown  in  the  figure. 

Next  let  us  for  comparison  substitute  a  lens  of  very  much 
longer  focus,  thirty  inches.  And  let  us  recede  to  such  a  distance 
that  the  image  of  the  nearer  tree  shall  occupy  precisely  the  same  height 
A  B  as  it  did  before.  To  accomplish  this  we  shall  be  obliged  to 
recede  to  the  distance  of  1500  feet.  How  will  now  the  second 
equal  tree  be  represented  ? 

Instead  of  measuring  six-tenths  of  an  inch,  as  in  the  previous 
case,  it  will  be  found  to  be  .79  inch,  or  very  nearly  eight-tenths. 
It  neither  stands  in  the  same  relation  of  height,  nor  does  it  occupy 
the  same  position,  but  is  represented  at  E  F. 

Let  us  next  substitute  a  lens  of  four  inches  focal  length.  In 
order  to  produce  an  image  of  the  first  tree  of  the  same  height  as 
in  the  first  case,  we  shall  be  obliged  to  advance  to  within  200 
feet  of  the  first  tree.  And  then  the  second  tree  will  be  found  to 
have  a  height  on  the  ground  glass  of  only  .33  inch,  or  one-third  of 
an  inch.  Its  place  will  also  be  totally  changed ;  and  it  will  be 
found  at  G  J,  showing  only  that  apparent  height  which  it  has  in 
the  figure. 

If  now  we  consider  the  equal  height  and  the  relative  position 
of  these  trees,  we  shall  see  that  the  image  formed  by  the  first  lens 
of  twelve  inch  focus  preserves  a  truthful  relation  between  these 
objects,  and  conveys  it  to  the  eye. 

On  the  contrary,  the  long  focus  lens  brings  the  second  tree  so 
far  forward,  and  gives  it  so  nearly  the  height  of  the  first,  that  we 
do  not  at  all  realize  that  it  is  so  much  farther  away.  The  eye  is 
completely  deceived.  And  this  fault  is  incident  to  all  lenses  of 


1  These  distances  are  always  measured  upon  the  line  of  sight  E  C ,  Fig.  76, 
and  will  he  presently  explained,  and  the  mode  of  determining  apparent  sizes 
explained. 


102 


PHOTOGRAPHIC  PERSPECTIVE. 


very  long  focus,  that  they  do  not  preserve  the  relative  planes  of 
distance ,  but  drag  objects  that  belong  to  the  middle  distance,  into 
the  foreground. 

The  fault  of  the  very  short  focus  lens  is  in  an  exactly  opposite 
direction.  The  second  tree  is  so  excessively  reduced  in  size  that 
the  eye  to  account  for  this  is  driven  into  one  or  other  of  two 
errors,  either  it  misconceives  the  height  -of  the  second  tree,  and 
imagines  it  to  be  smaller,  or  it  misconceives  the  distance ,  and 
imagines  the  object  to  be  much  farther. 

So  the  vanishing  point  which  in  a  correct  representation  is  at 
the  point  V,  is,  in  the  short  focus  lens,  drawn  in  to  V',  and,  with 
the  long  focus  lens,  carried  far  beyond  the  limits  of  the  diagram. 

The  author  has  chosen  trees  to  illustrate  this  point,  but  the 
principle  is  of  course  universally  true.  So  the  side  of  a  house, 
seen  at  a  suitable  distance,  and  with  a  lens  of  moderate  focal  length, 
may  present  the  appearance  A  B  C D,  Fig.  71.  When  we  approach 
nearer,  and,  as  before,  substitute  a  lens  of  smaller  focal  length, 


Fig.  71. 


so  as  to  keep  some  one  line  A  B  of  the  same  height  as  before, 
the  image  assumes  the  appearance  ABch. 

There  is  a  certain  subtlety  in  applying  these  principles  to  prac¬ 
tice,  which  requires  close  attention.  Although  the  character  of 
the  image,  as  distinguished  from  its  mere  size,  depends  upon  the 
distance  to  which  we  go  from  the  object,  and  not  upon  the  lens, 
yet,  nevertheless,  lenses  of  small  focal  lengths  give  almost  always 
very  incorrect  pictures,  because  such  lenses  are  brought  too  near 
to  the  objects,  and  the  sharp  perspective  angle  c  B  A  results, 
which  is  always  offensive,  and  may  legitimately  be  termed  incor¬ 
rect,  because  it  gives  incorrect  conceptions  of  the  object  deli¬ 
neated.  In  some  cases  where  an  excessively  sharp  perspective 
angle  is  introduced,  the  building  will  actually  seem  to  be  falling 
forwards,  and  this  may  happen  just  as  easily  with  a  draughts¬ 
man’s  sketch  as  with  a  photographic  view.  In  the  latter  case  a 
longer  focus  lens  should  be  used,  and  taken  to  a  greater  distance. 


PHOTOGRAPHIC  PERSPECTIVE. 


103 


If,  for  example,  it  be  required  to  photograph  a  large  edifice,  so 
that  the  image  shall  be  only  three  inches  high,  and  we  take  a 
four-inch  lens  and  go  to  such  a  distance  as  will  secure  the  size 
required,  we  shall  get  a  picture  with  the  sharp  angle  C  B  A  ;  but 
if  we  take  a  lens  of  eight  to  ten  inch  focus,  and  go  to  such  a  dis¬ 
tance  that  the  image  is  reduced  to  the  same  height,  three  inches, 
we  shall  get  a  natural,  angle  CB  A,  the  actual  apparent  height 
A  B  remaining  the  same  in  both  cases,  precisely  as  exemplified  in 
the  cases  already  considered. 

As  the  principles  here  involved  are  of  much  importance  in  ob¬ 
taining  satisfactory  representations  of  buildings  of  all  descriptions, 
the  author  subjoins  some  illustrations  that  will  exemplify  them 
strikingly.  Fig.  72  gives  a  view  of  Girard  College  as  repre- 


Fig.  72. 


Girard  College. — View  exemplifying  the  exaggerated  perspective  produced  by  very  short  focus 

lenses. 

sented  by  a  very  short  focus  lens.  The  sharpness  of  the  upper 
angle  will  be  remarked,  and  also  the  unnatural  effect  given  to  the 
building  in  consequence  of  the  vanishing  points  being  so  much 
drawn  in. 

On  the  other  hand,  Fig.  78  shows  the  same  building  as  repre¬ 
sented  by  a  much  longer  focus  lens,  not  planted  on  the  same  spot, 

Fig.  73. 


Girard  College. — View  showing  the  correct  perspective  produced  by  longer  focus  lenses. 


104 


PHOTOGRAPHIC  PERSPECTIVE. 


for  then  the  result  would  have  been  a  much  larger  picture,  with 
the  same  angles  as  the  former.  But  when  the  longer  focus  lens 
is  made  to  produce  a  picture  of  about  the  same  size  as  the  other 
by  removing  it  to  a  greater  distance,  we  then  get  the  effect  shown 
in  Fig.  73,  in  which  the  perspective  is  natural  and  agreeable  to 
the  eye. 

In  order  to  illustrate  the  principle  more  fully,  the  author  sub¬ 
joins  two  oblique  views  of  a  Gothic  front,  the  one  (Fig.  74)  show- 


Fig.  74. 


West  Front  of  St.  Mark’s  Church,  Philadelphia. — Exaggerated  perspective  of  short  focus  lens. 

ing  the  exaggerated  and  unpleasing  effect  of  the  short  focus,  by 
which  the  correct  relation  between  the  nearer  and  farther  por¬ 
tions  is  destroyed. 


Fig.  75. 


St.  Mark’s.— Correct  perspective  of  longer  focus  lens. 


On  the  other  hand,  Fig.  75  shows  the  same  front  seen  from  the 
same  direction,  but  as  represented  by  a  longer  focus  lens  placed 
at  a  greater  distance. 


PHOTOGRAPHIC  PERSPECTIVE. 


105 


The  practical  application  of  these  rules  is  farther  somewhat 
complicated  by  the  fact  that  it  is  necessary  to  take  into  consider¬ 
ation  the  actual  size  of  the  picture ;  for  it  is  an  unquestionable 
fact  that  the  eye  will  support  perspective  angles  in  a  large  picture , 
that  it  will  not  in  a  small  one. 

If,  for  example,  we  take  a  small  picture  G  B  A  (Fig.  69),  and 
magnify  it  considerably,  we  shall  find  that  the  perspective  angles, 
too  sharp  before,  lose  this  effect,  and  seem  more  natural.  (The 
experiment  is  a  surprising  one,  and  must  be  tried  to  be  appreciated.) 
This  is  one  reason  why  the  small  photographs  taken  with  very 
short  focus  lenses  are  so  much  improved  by  magnifying  them. 
Their  caricatured,  or,  as  it  is  technically  termed,  violent ,  perspec¬ 
tive,  intolerable  in  such  small  pictures,  becomes  more  endurable 
in  the  large  one.  On  the  other  hand,  a  large  picture,  in  which 
the  perspective  is  appropriate  and  suitable  for  its  size,  cannot  be 
reduced  without  injury.  Even  if  the  reduction  be  absolutely 
perfect,  as  when  executed  by  a  copying  camera,  the  character  of 
the  design  is  destroyed.  Engravers  know  this,  and  know  that  a 
large  architectural  drawing  cannot  be  reduced  with  advantage; 
and  the  same  truth  is  recognized  by  all  artists.  Ruskin  remarks 
that  true  perspective  is  infinite  and  unreducible  in  its  nature. 
To  every  size  of  representation  there  is  a  certain  size  of  perspec¬ 
tive  angle  appropriate,  or  rather  the  appropriate  size  lies  within 
certain  limits,  and  these  are  only  to  be  fixed  by  judgment  and 
cultivated  taste. 

Farther,  it  is  to  be  remarked,  that  as  in  every  photographic 
image  the  focal  length  of  the  lens  corresponds  with  the  distance 
of  the  eye  from  the  section  on  the  window-pane  before  spoken 
of,  it  follows  that  every  photographic  picture,  to  give  a  correct 
impression,  should  be  held  from  the  eye  at  a  distance  equal  to 
the  focal  length  of  the  lens  with  which  it  was  taken.  It  will  be 
at  once  apparent  that  a  view  taken  with  a  lens  of  four  or  five 
inches  focus,  cannot  be  held  that  near  to  the  eye  of  a  person  with 
ordinary  sight.  It  follows,  therefore,  that  such  lenses  never  can 
give  truthful  delineations  of  scenery.  They  may  make  pretty 
pictures,  but  these  are  wholly  incorrect,  as  many  must  have 
noticed.  A  garden  becomes  a  park.  The  farther  part  of  a  house 
is  represented  on  so  much  smaller  a  scale  than  the  nearer  part, 
that  the  eye,  accustomed  to  correct  representations,  is  deceived, 
and  imagines  the  farther  part,  by  reason  of  its  smallness,  to  be 
much  farther  away  than  it  is.  And  thus  the  farther  part  being 
8 


106 


PHOTOGRAPHIC  PERSPECTIVE. 


dragged  away,  the  house  appears  to  stretch  much  farther  back 
than  it  does  in  reality,  and  consequently  to  be  much  larger. 
Distant  objects  are  dwarfed  down,  mountains  become  hills,  if  they 
but  stand  clear  of  the  foreground. 

As  we  see  objects  best  at  about  10  or  12  inches  from  the  eye, 
this  would  appear  to  be  about  the  best  focal  length  for  a  lens. 
Still,  as  the  eye  does  not  discriminate  closely  in  these  matters,  and 
is  very  tolerant  within  limits,  lenses  of  all  focal  lengths,  from  7 
to  15  or  16  inches,  may  be  employed  with  advantage.  Beyond 
this,  the  pictures  become  flat  and  tame,  and  the  impression  of 
solidity  is  insufficient.  The  round  pillar  looks  like  a  flat  pilaster. 

In  these  cases  the  defect  is,  to  some  extent,  corrected  by  remov¬ 
ing  the  picture  considerably  farther  from  the  eye.  We  can  here 
alleviate  the  evil  in  a  way  that  we  could  not  with  the  pictures  of 
the  short  focus  lens.  Still,  the  effects  are  not  good. 

Portraiture. — Perspective  is  not  without  its  bearing  upon  por¬ 
traiture.  All  portraits  taken  with  short  focus  lenses  are  incor¬ 
rect.  The  nose  is  represented  upon  too  large  a  scale  for  the  rest 
of  the  face,  because  it  is  nearer  the  lens.  And  it  is  still  worse 
with  the  hands  and  feet,  if  visible.  If  two  or  more  persons  be 
included,  their  relative  sizes  are  not  properly  preserved,  unless 
they  stand  exactly  in  line  side  by  side.  This  incorrectness  be¬ 
comes  quite  striking  where  one  person  stands  behind  the  other, 
and  a  lens  of  4  or  5  inch  focus  is  employed.  The  fault  in  all 
such  cases  depends  upon  the  use  of  lenses  of  too  short  focal 
length,  in  order  to  work  in  a  short  gallery,  and  work  very 
quickly.  By  using  a  lens  of  7  or  8  inch  focal  length,  and  going 
sufficiently  far  from  the  sitter  to  get  the  reduction  desired,  all 
parts  of  the  person  will  be  harmoniously  rendered,  and  the 
different  persons  composing  a  group  will  be  represented  in  correct 
perspective  proportion,  whether  near  to,  or  at  some  distance  from 
the  foremost  figure. 

§  2. — Plane  Projection  and  Apparent  Size, 

Plane  Projection. — In  the  foregoing  we  have  always  considered 
the  perspective  as  referred  to  ordinary  or  plane  projection,  that 
is,  the  surface  of  the  image  is  perpendicular  to  the  line  of  vision. 
The  eye  looks  in  the  direction  E  C  at  the  view  A  C  B,  which,  as 
delineated,  is  supposed  to  be  projected  on  the  screen  or  paper 
A'  B\  held  perpendicularly  to  the  line  of  sight  E  C. 


PLANE  PROJECTION  AND  APPARENT  SIZE.  107 


This  enables  us  at  once  to  fix  the  apparent  size  that  any  object 
will  have  in  a  plane  projection,  whether  it  be  drawn  or  photo¬ 
graphed.  For  suppose  the  paper 
to  be  held  at  one  foot  from  the 
eye,  that  is,  that  E  O  is  one 
foot.  If  the  tree  C  is  a  hundred 
feet  from  the  eye,  that  is,  one 
hundred  times  E  C' ,  which  is 
now  our  scale,  it  will  be  dimin¬ 
ished  one  hundred  times.  There¬ 
fore,  if  it  is  fifty  feet  high,  it  will 
be  Tepresented  on  A'  Br  as  half 
a  foot.  Precisely  the  same  is 
true  of  a  photographic  represen¬ 
tation.  If  the  lens  is  at  E ,  and  has  a  focal  length  E  F of  one  foot, 
the  tree  fifty  feet  high  and  one  hundred  feet  distant,  will  appear 
in  the  negative  six  inches  in  height. 

If  another  tree  of  exactly  the  same  height  be  situated  at  A,  then, 
although  that  tree  may  be  distant  half  as  far  again,  it  will  be 
represented  at  A '  of  the  same  size  as  O'.  It  appears  at  first  anoma¬ 
lous  that  two  objects  of  the  same  size,  at  very  different  distances, 
should  have  an  equal  size  in  the  image  or  picture ;  but  this  ano¬ 
maly  disappears  by  reflecting  that,  as  the  image  is  supposed  to 
be  held  square  before  the  eye,  the  image  of  the  tree  A  at  A'  is 
farther  from  the  eye  than  the  image  of  the  tree  C  at  G\  so  that 
E  A'  stands  in  the  same  relation  to  E  A  as  E  C'  to  E  C ,  and, 
therefore,  if  a  sketch  of  a  given  size  held  at  Cf  would  exactly 
cover  the  real  tree  (7,  then  a  sketch  of  the  same  size  held  at  A' 
would  exactly  cover  the  real  tree  A. 

It  follows,  therefore,  that  all  objects  of  an  equal  size  upon  a  line 
A  B)  perpendicular  to  the  line  of  sight  E  C,  are  represented  of  equal 
size  in  the  plane  projection  A'  Bj  whatever  he  their  distances  from 
the  eye. 

An  instance  of  this  occurs  in  all  drawings  of  fronts  of  build¬ 
ings  or  rows  of  houses  of  equal  heights,  when  the  observer  is 
supposed  to  stand  exactly  in  front.  In  the  picture  the  houses 
have  the  same  actual  height  at  the  ends  of  the  row,  as  in  the 
middle,  although  they  may  be  much  more  distant.  So  in  the  de¬ 
lineation  of  the  front  of  the  building,  seen  directly  in  front,  the 
roof  line  is  parallel  to  the  base  line,  and  shows  no  tendency  to 
meet  it. 


Fig.  76. 


108 


PHOTOGRAPHIC  PERSPECTIVE. 


§  3. — Panoramic  Projection. 

This  form  of  projection  is  never  used  in  architectural  delinea¬ 
tions,  and  has  only  lately  attracted  attention  in  photography, 
from  the  introduction  of  the  revolving  camera. 

In  plane  projection  the  image  is  projected  upon  a  plane  sur¬ 
face,  as  the  name  indicates ;  in  the  panoramic  it  is  thrown  upon 
one  that  is  cylindrical. 

The  curved  surface  A '  C'  B'  receives  the  image,  and  as  the  point 
A’  is  no  farther  from  the  eye  than  C\  it  follows  that  of  the  two 
equal  objects  A  and  (7,  A  is  represented  smaller  just  in  propor¬ 
tion  to  the  actual  distance,  so 
that  if  the  distance  E  A  be 
half  as  long  again  as  F  G ,  the 
tree  A  will  have  only  two- 
thirds  the  apparent  height  of 
the  equal  tree  C. 

The  representations  afforded 
by  panoramic  perspective  are 
correct  only  when  they  are 
received  on  a  curved  surface  and  so  viewed.  If  printed  on 
paper,  the  paper  must  be  curved  into  the  arc  A'  C'  B '  of  a  circle, 
whose  radius  is  the  focal  length  of  the  lens  with  which  they  were 
taken.  If  such  prints  be  laid  flat  (as  they  always  are  in  practice), 
everything  is  distorted.  With  landscapes  this  may  be  tolerated, 
that  is,  the  eye,  if  unfamiliar  with  the  scene,  may  not  detect  the 
falsification,  and  the  general  effect  may  be  pleasing.  But  as  soon 
as  this  mode  of  representation  is  applied  to  architecture,  its 
faults  become  strikingly  apparent.  If  the  front  of  a  building 
be  represented,  the  horizontal  right  line  of  the  roof  or  cornice 
becomes  a  curve  with  the  ends  pointing  downwards.  The  base 
line  of  the  building  becomes  another  curve,  with  the  ends  point¬ 
ing  upwards.  All  horizontal  lines  become  curves,  but  vertical 
lines  still  remain  straight,  because  the  projection  plane  was 
curved  only  in  a  horizontal  direction ;  it  was  cylindrical,  and  the 
vertical  right  lines  in  nature  were  all  represented  by  vertical 
right  lines  on  the  cylindrical  surface. 


Fig.  77. 


PART  III. 


PHOTOGRAPHIC  MANIPULATIONS. 


CHAPTER  I. 

THE  DARK  ROOM. 

§  1. — Regulation  of  Light. 

The  dark  room  in  which  the  operations  of  sensitizing  and 
development  are  to  be  conducted,  is  most  commonly  made  by 
partitioning  off  a  portion  of  a  larger  room  for  this  purpose.  It 
consequently  happens  not  unfrequently  that  this  room  is  lighted 
only  by  an  opening  into  the  larger  room,  and  has  no  window 
communicating  with  the  exterior.  This  is  a  serious  evil,  and 
one  to  be  avoided  if  possible.  No  sufficient  ventilation  can  be 
obtained  except  from  a  window  upon  the  street  or  yard,  and 
for  want  of  this,  the  operator’s  health  is  exposed  to  suffer  severe 
injury. 

The  Window. — When  access  can  be  had  to  the  open  air,  it  is 
desirable  that  the  window  of  the  dark  room  shall  not  be  so 
situated  as  to  receive  the  direct  rays  of  the  sun.  If  this  can¬ 
not  be  wholly  avoided,  it  is  better  to  have  the  sun  fall  obliquely, 
and  later  in  the  day,  rather  than  perpendicularly,  or  in  the 
morning ;  therefore  a  northwest  exposure  will  be  best,  if  it  can 
be  arranged. 

It  is  much  better  to  have  a  good  light  in  the  dark  room  than 
to  work  by  a  faint  one,  and  this  can  always  be  accomplished  by 
using  proper  precautions.  The  window  need  not  be  small,  if  it 
is  properly  protected. 

There  are  two  methods  in  common  use:  the  use  of  yellow  glass, 
and  the  coloring,  or  otherwise  guarding  of  common  glass. 

The  yellow  glass  sold  in  the  shops,  even  when  the  darkest 
shades  are  used,  is  not  in  itself  a  sufficient  protection.  Even 
when  direct  sunlight  does  not  fall  upon  the  window,  light  enough 


110 


PHOTOGRAPHIC  MANIPULATIONS. 


will  enter  to  impress  a  plate ;  this  the  writer  can  assert  from 
experience.  As  an  additional  protection,  a  shade  of  brown  hol- 
land  is  useful,  which  in  dark  weather  can  be  rolled  up. 

Pasting  yellow  paper,  such  as  is  made  for  common  yellow  en¬ 
velopes,  gives  an  excellent  protection  if  the  paper  is  stout,  and  if 
the  sun  does  not  fall  directly  on  the  window,  this  will,  in  many 
cases,  be  sufficient.  The  paper  should  be  cut  to  the  exact  size  of 
the  panes,  and  attached  by  a  border  of  paste.  In  this  way  the 
free  open  and  shutting  of  the  sash  is  not  interfered  with.  The 
yellow  glass  is  of  course  preferable. 

For  a  long  time  past,  the  writer  has  substituted  green  glass  for 
yellow.  The  orange-yellow  shade  of  color  imparted  to  light  by 
the  glass  in  ordinary  use  is  very  trying  to  the  eyes  of  many 
persons.  The  green  light,  on  the  contrary,  is  pleasant  both  for 
the  operation  of  preparing  the  plates  and  for  developing.  A 
tolerably  dark,  but  not  too  dark,  shade  will  be  proper. 

The  light  used  may  be  (whether  green  or  yellow  glass  be  em¬ 
ployed)  either  ordinary  daylight,  or  artificial  light.  The  latter 
has  the  advantage  that  it  may  be  had  always  of  equal  power, 
which  is  of  great  use  in  judging  of  the  density  of  a  negative 
during  development.  In  employing  daylight  through  colored 
glass,  more  mistakes  will  be  made  as  to  the  density  of  the  nega¬ 
tive  than  when  an  artificial  light  of  uniform  strength  is  used. 

If  a  window  is  used  for  illumination,  it  should  not  be  too 
small,  so  that  the  light,  after  being  thoroughly  divested  of  its 


actinic  elements,  may  still  be  sufficiently  abundant 


Fig.  78.  to  render  all  operations  easy.  Ordinary  print 


should  be  read  with  ease  in  the  dark  room,  and 
this  is  not  inconsistent  with  absolute  immunity 
from  fogging,  if  the  precautions  just  mentioned 
have  been  suitably  taken. 


But  a  window  for  occasional  opening,  is  not  in 
itself,  by  any  means,  a  sufficient  mode  of  ventila¬ 
tion.  In  the  roof  of  the  room,  a  five  or  six-inch 
pipe  should  be  set,  the  exterior  part  of  which  is 
bent  twice  at  right  angles,  so  as  to  point  down¬ 
wards;  in  this  way  neither  light  nor  rain  can  enter. 
An  opening  communicating  with  the  outer  air, 


near  the  floor,  for  the  admission  of  air,  is  also  very  desirable. 
A  slanting  board  is  nailed  against  it,  which  freely  lets  pass  the 
air,  but  excludes  the  light. 


THE  DARK  ROOM. 


Ill 


Or  a  Ventilating  Box  may  be  employed.  Such  a  box  is  repre¬ 
sented  in  Fig.  79.  It  is  easily  put  together  out  of  a  few  boards. 
A  hole  is  cut  into  the  partition  of 
the  dark  room,  corresponding  in 
size  to  the  opening  Gr  at  the  right 
hand  end  of  the  box,  from  which 
one  side  A  B  C  D,  is  here  supposed 
to  be  removed,  in  order  to  show  the 
interior  arrangement,  and  then  the 
box  is  fastened  close  over  the  hole. 

The  air  enters  at  the  opening  H,  in 
the  bottom  of  the  box,  and  passes 
through  the  partition,  whilst  the 
light  is  effectually  excluded  by  the  cross  pieces  E  and  F.  Two 
such  boxes  should  be  used,  one  for  the  ingress,  the  other  for  the 
egress  of  the  air.  The  former  is  better  placed  so  as  to  commu¬ 
nicate  with  the  outside  air.  If  this  cannot  be  done,  and  both 
must  be  placed  inside,  one  should  be  near  the  floor,  the  other 
near  the  ceiling. 


§  2. — Arrangement. 

The  arrangement  of  the  room  will  depend  so  much  upon  its 
size  and  shape,  that  it  is  difficult  to  give  any  general  directions. 
But  it  may  be  said,  that  the  place  for  developing  should  be  in 
front  of  the  window,  and  that  near  by  it  should  be  a  sink  with  a 
tap  for  washing.  The  tap,  in  fact,  should  be  so  at  hand  that 
water  can  be  made  to  flow  over  the  negative  at  any  instant  to 
stop  its  development.  This  is  very  urgent,  and  any  arrangement 
that  does  not  accomplish  this  is  exceedingly  defective. 

A  good  plan  is  to  have  a  shelf  eighteen  inches  wide  round 
three  sides  of  the  room.  The  height  of  the  shelf  will  depend 
upon  whether  the  operator  develops  sitting  or  standing.  If  the 
former,  the  shelf  should  be  just  high  enough  to  put  the  knees 
under,  and  no  more.  If  standing,  it  should  have  a  somewhat 
greater  height. 

If  vertical  baths  are  used  for  sensitizing,  they  should  not 
stand  on  this  shelf,  but  should  be  let  into  it,  so  that  the  top  of 
the  bath  will  be  level  with  the  shelf ;  at  least  this  is  advisable  if 
it  is  intended  to  do  this  part  of  the  work  seated. 

If  the  fixing  is  done  in  the  dark  room,  the  fixing  bath  and  all 
utensils  connected  with  this  part  of  the  work,  should  be  as  far  as 


112 


PHOTOGRAPHIC  MANIPULATIONS. 


possible  from  the  sensitizing  baths,  and  the  utmost  care  should 
be  taken  to  avoid  the  introduction  of  the  minutest  portion  of  the 
hyposulphite  into  the  silver  bath,  to  which  it  would  be  fatal. 

The  figure  below  represents  an  arrangement  adopted  by  the 
author,  where  it  was  a  great  object  to  save  space.  A  wide  shelf 


Fig.  80. 


to  be  used  as  a  table,  runs  round  three  sides.  At  A  are  the 
sensitizing  baths,  and  near  A  is  a  small  window  of  yellow  glass, 
to  coat  the  collodion  and  manage  the  sensitizing  by.  (This  win¬ 
dow  is  by  no  means  essential.)  Opposite  to  B  is  the  principal 
window,  looking  north,  and  opening  to  the  open  air.  In  front  of 
it  at  B ,  is  the  tray  or  sink  over  which  the  developing  is  done. 
This  window  comes  down  so  that  the  bottom  of  the  lowest  pane 
is  level  with  the  top  of  the  table.  A  window  with  a  high  sill  in 
a  dark  room  is  a  great  nuisance.  At  C  is  the  sink  with  a  tap  of 
water  over  it.  At  D  is  the  fixing  bath  of  hyposulphite. 

A  double-kneed  pipe  is  set  into  the  roof,  and  fresh  air  is  in¬ 
troduced  at  the  floor  from  the  outside,  as  before  described. 

The  dark  room  should  be  kept  clean  and  free  from  dust.  The 
chemicals  that  emit  fumes  should  be  kept  elsewhere,  and  care  be 
taken  to  avoid  spilling  hyposulphite  solutions  about,  because 
whatever  substances  are  scattered  over  the  floor  in  solution  soon 
dry,  and  are  ground  off  into  dust  by  the  feet.  This  dust  may 
rise  and  settle  again  in  vessels  and  solutions.  All  such  foreign 
matter  is  injurious,  and  nothing  more  so  than  hyposulphite. 

Too  much  shelf  space  in  the  dark  room  is  undesirable  ;  it  is  an 
invitation  to  leave  things  there  that  are  better  away.  No  worse 
mistake  can  be  made  than  that  of  keeping  chemicals  in  the  dark 
room.  It  happens  that  most  of  the  substances  used  for  after- 
intensifying  emit  vapors  that  tend  strongly  to  produce  fogging, 
and  especially  sulphide  of  potassium  (liver  of  sulphur)  and 
Schlippe’s  salt.  Old  solutions  containing  vegetable  or  other  or- 


THE  DARK  ROOM. 


113 


ganic  matter  liable  to  turn  sour  or  putrefy,  are  very  injurious.. 
A  long  succession  of  failures  was  once  traced  by  a  professional 
photographer  to  a  bottle  of  sulphocyanide  of  ammonium,  either 
originally  impure,  or  into  which  something  had  been  dropped 
that  had  set  up  a  decomposition.  In  a  word,  there  are  so  many 
suspicious  substances,  and  injury  when  it  comes  is  so  intensely 
vexatious  and  so  difficult  to  trace  out,  that  it  is  best  to  be  on  the 
safe  side,  and  to  absolutely  interdict  the  presence  of  anything  in 
the  dark  room  that  is  not  needed  for  the  coating,  sensitizing,  and 
developing,  to  the  exclusion  of  all  other  operations. 

It  is  still  worse  when  the  dark  room  is  used  as  a  work  room 
for  chemical  operations,  and  when  torrents  of  gases  are  gene¬ 
rated  that  permeate  the  wood  work  and  plastering,  and  slowly 
ooze  out  again  for  weeks. 

Foul  drains,  or  pipes  communicating  with  sewers  may  intro¬ 
duce  gases  that  will  interfere  with  the  work.  The  presence  of 
turpentine  and  of  fresh  paint  have  been  affirmed  to  interfere  with 
negative  work  very  seriously. 

But  the  simple  exclusion  of  these  sources  of  trouble  is  not  in 
itself  sufficient.  A  complete  ventilation  is  required,  and  a 
copious  admission  of  pure  air  into  the  dark  room  is  a  matter 
upon  which  the  photographer’s  health,  possibly  even  his  life,  may 
depend.  The  recklessness  shown  by  many  in  these  respects  is 
incredible,  and  can  only  be  explained  by  an  entire  want  of  know¬ 
ledge  of  the  dangers  incurred.  It  is  a  fact  familiar  to  physicians 
that  a  daily  exposure,  even  for  a  limited  time,  to  an  atmosphere 
impregnated  with  noxious  fumes  will  do  serious  mischief,  even 
when  no  inconvenience  is  felt  at  the  time.  Our  senses  rapidly 
familiarize  themselves  with  injurious  emanations,  and  cease  to 
give  us  notice  of  them,  even  when  they  are  silently  and  steadily 
doing  their  work  of  destruction. 

Nor  should  any  photographer  require  an  assistant  or  person 
employed  to  do  work  which  he  would  avoid  himself  by  reason 
of  its  insalubrity.  This,  however,  is  often  done,  and  is  always 
thoroughly  unjustifiable.  Frequently  the  person  so  exposed  is 
ignorant  of  his  own  danger. 

It  is  desirable  that  the  temperature  of  the  dark  room  should  not 
differ  very  materially  from  that  of  the  glass  room. 


114 


PHOTOGRAPHIC  MANIPULATIONS. 


CHAPTER  II. 

THE  GLASS  ROOM. 

§  1. — General  Remarks. 

No  subject  concerns  the  professional  photographer  more  deeply 
than  the  glass  room.  Chemicals,  lenses,  and  cameras  he  can 
always  obtain  of  excellent  quality  from  dealers  of  reputation, 
but  in  the  construction  of  the  glass  room  he  must  depend  to  a 
large  extent  upon  himself,  acting  under  such  information  and  in¬ 
struction  as  he  can  obtain.  It  is  certain  that  a  very  clever  ope¬ 
rator  will  occasionally  obtain  good  pictures  in  almost  any  glass 
room ;  this  is  not,  however,  what  is  wanted.  The  disposition  of 
light  should  be  such  as  to  facilitate  to  the  utmost  the  really  diffi¬ 
cult  task  of  regular  success. 

If  any  intelligent  observer  will  place  himself  in  a  room  lighted 
from  several  different  directions,  and  taking  a  looking-glass  in  his 
hand,  will  observe  his  own  face,  as  he  stands  in  very  different 
parts  of  the  room,  with  very  different  illuminations,  he  will  see 
a  wonderful  change  as  regards  feature,  character,  and  expression. 
Now,  the  object  of  the  glass  room  is  to  obtain  from  each  face  its 
best,  and  at  the  same  time,  also,  its  characteristic  expression. 

If  the  observer  with  his  hand-glass  carefully  notices  the  effects 
of  different  lights  upon  his  features,  he  will  be  especially  struck 
with  the  three  following  facts : — 

1.  That  a  level  light,  coming  directly  in  front ,  flattens  all  the 
features. 

2.  That  a  light  directly  from  above  produces  an  opposite  effect, 
exaggerating  the  projection  of  the  brows  and  nose,  rendering 
the  eyes  cavernous,  and  drawing  out  the  cheek  bones. 

3.  That  a  level  light  from  one  side  produces  a  most  unpleasant 
effect,  causing  what  is  known  as  a  “  hatchet”  expression  of  face. 

Pursuing  his  trials  further,  he  will  find  that  the  right  light  to 
use  consists  in  a  combination  of  the  three  into  a  front  upper -side 
light.  To  produce  this  light  is  the  great  object  of  the  disposition 
of  the  glass  room ;  bearing  in  mind  that  for  different  sitters  a 
variation  of  light  must  be  at  command,  and  that  as  the  position, 
strength,  and  character  of  the  light  vary  at  different  hours  of  the 
day,  the  means  of  compensating  for,  and  correcting  these  changes, 
must  be  at  hand. 


THE  GLASS  ROOM. 


115 


Selection  of  Glass  for  Glazing. — The  experiments  of  Mr.  Gaf- 
field  and  others  have  shown  that  very  pure  white  specimens  of 
glass  are  more  apt  to  change  color  by  the  continued  action  of 
sunlight,  than  those  that  are  a  little  colored.  The  explanation 
appears  to  be  that  the  freedom  from  color  is  obtained  by  the 
addition  of  manganese  in  the  making  of  the  glass,  and  that  glass 
to  which  manganese  has  been  added  is  apt  to  change  by  sunlight 
to  a  color  which  is  sometimes  purple,  sometimes  golden ;  in 
either  case  greatly  obstructing  the  passage  of  the  active  rays. 
It  was  found  that  fine  white  plate  glass  was  the  most  liable  to 
change  of  all  the  sorts  examined.  A  light  bluish-green  window- 
glass  is  that  which  is  most  suitable  for  glazing  the  glass  room. 
It  would  be  desirable  if  glass  manufacturers  would  furnish  glass 
expressly  for  glazing  photographic  rooms,  guaranteed  free  from 
manganese. 


§  2. — Ridge  Roof  Construction. 

By  far  the  best  light  for  the  portraitist  is  the  pure,  soft,  diffusive 
light  that  comes  from  a  northern  exposure.  An  abundant  supply 
of  this  light  is  of  the  highest  value.  It  is  best,  therefore,  that 
the  length  of  the  glass  room  should  be  east  or  west,  and  that  the 
north  light  should  be  received  on  one  side.  The  best  photo¬ 
graphers  all  over  the  world  are  now  pretty  generally  agreed  in 
preferring  what  is  known  as  the  Ridge  Roof  System  of  Construc¬ 
tion,  a  section  of  which  in  various  forms  is  shown  in  the  figures. 


Fig.  81.  Fig.  82.  Fig.  83. 


The  single  line  represents  the  glazed  parts;  the  double  line,  ordi¬ 
nary  walls,  ceiling,  &c. 

Of  these  forms  A  is  the  preferable  one.  Great  differences  of 
opinion  exist  as  to  the  best  pitch  to  give  the  light  side  of  the 
roof.  Two  different  inclinations  are  shown  in  Fig.  81  by  the  line 
above,  and  that  below,  G.  Some,  however,  make  it  still  flatter 


116 


PHOTOGRAPHIC  MANIPULATIONS. 


than  the  flattest  of  these,  even  as  little  slope  as  two  inches  to  the 
foot.  Others  again  will  give  it  a  pitch  of  thirty  degrees  or  more. 
Fisr.  84  shows  a  perspective  view  of  the  interior  of  this  con¬ 
struction.  The  principal  length 
from  front  to  back  is,  of  course, 
east  and  west,  the  glazed  side 
being  towards  the  north.  The 
glazing  is  carried  half  way  or 
thereabouts ;  at  least  it  is  better 
that  it  should  not  go  farther, 
in  order  that  the  camera  may 
be  well  protected  from  the  light. 
It  will  be  necessary,  or,  at  least, 
far  better,  to  have  a  screen  so 
interposed  as  to  shut  off  useless 
and  injurious  light  from  strik¬ 
ing  the  camera  from  the  glazed 
portions.  It  is,  indeed,  a  most 
excellent  canon,  that  the  eye ,  if  placed  in  the  position  which  the  lens  is 
to  occupy ,  shall  not  see  any  uncovered  glass.  It  should  never  be  for¬ 
gotten  that  neglect  of  this  will  diminish  the  brilliancy  of  the  image. 

The  relation  between  the  dimensions  of  the  glass  house  will 
be  better  understood  by  the  perspective  drawing  of  its  exterior 


Fig.  85. 


view,  Fig.  85.  If  a  perpendicular  be  dropped  from  the  top  line 
of  the  glass  to  the  floor,  its  height,  A  B,  represents  the  extreme 
height  of  the  glass.  A  line  C  D  is  drawn  at  right  angles  to  it, 
and  the  angle  C  D  B  is  that  of  the  inclination  of  the  roof.  The 
glazing  begins  at  the  height  E  H  from  the  floor.  HD  is  the 
height  from  the  floor  at  which  the  top  light  commences. 

The  pitch  of  the  upper  skylight  is  usually  measured  by  giving 
the  angle  BDC.  But  as  few  carpenters  are  able  to  lay  off  a  roof 


Fig.  84. 


THE  GLASS  ROOM. 


117 


at  a  given  angle,  the  following  table  will  be  found  useful.  It 
gives  the  actual  height  B  C  for  any  desired  angle,  taking  the 
breadth  D  0  as  10,  from  which  the  height  is  easily  found  for  any 
other  breadth,  greater  or  less. 


TABLES  OF  INCLINATION  IN  FEET  FOR  A  GIVEN  ANGLE  OF  PITCH. 


Table  I. 

Angle  of  pitch  of  roof  =  10°  ;  if  depth  C  D 

=  10,  height  B  C  =  1.76. 

Angle 

tt 

“  =  12°  “  “ 

tt  tt 

“  =  2.13. 

Angle 

t; 

tt  _  jrjo  tt  tt 

tt  tt 

“  =2.68. 

Angle 

tt 

“  =20°  “  “ 

tt  tt 

“  =3.64. 

Angle 

t. 

“  =.25°  “  “ 

tt  tt 

“  =  4.66. 

Angle 

tt 

II 

05 

O 

o 

tt  tt 

“  =  5.77. 

Angle 

it 

it  _  350  tt  tt 

tt  tt 

“  =  7.00. 

Angle 

tt 

It  __  4QO  tt  tc 

tt  tt 

“  =  8.40. 

That  is,  with  a  pitch  of  10°,  the  roof  will  rise  1.76  (1}  nearly) 
feet  in  ten,  and  so  on  for  other  inclinations.  To  exemplify  the 
use  of  this  table :  Suppose  it  be  intended  that  the  skylight  shall 
have  a  pitch  of  20°,  that  the  room  is  22  feet  wide,  and  that  the 
skylight  shall  come  perpendicularly  over  12  feet  of  these  22, 
what  perpendicular  height  must  the  carpenter  give  the  upper 
edge  B  of  the  skylight  above  its  lower  edge  DG?  or,  in  other 
words,  if  C  D  is  to  be  12  feet,  what  height  must  B  C  have  that 
the  roof  may  pitch  20°  ? 

Beferring  to  the  table,  we  get  for  20°  the  height  corresponding 

to  10  feet  of  base,  viz. . 3.64 

For  each  additional  foot  we  add  one-tenth  of  this,  viz.,  for 

2  feet . .73 

And  find  4Ty0  feet,  or  4  feet  4J  inches  nearly  .  .  4.37 

The  following  table  shows  the  perpendicular  height  for  differ¬ 
ent  angles  when  the  length  of  slant  line  B  D  is  given : — 


Table  II. 


Angle  of  pitch 

=  10°, 

slant  line  B  D 

=  10,  the  height  B  C  =  1.73. 

Angle 

tt 

=  12° 

“ 

tt 

tt  tt 

“  =  2.08. 

Angle 

tt 

=  15° 

tt 

tt 

tt  tt 

“  =2.59. 

Angle 

tt 

=  20° 

tt 

tt 

tt  tt 

“  =  3.42. 

Angle 

tt 

=  25° 

tt 

tt 

tt  tt 

“  =4.22. 

Angle 

1 1 

=  30° 

tt 

tt 

tt  tt 

“  =  5.00. 

Angle 

tt 

=  35° 

tt 

tt 

tt  tt 

“  =  5.73. 

Angle 

tt 

=  40° 

tt 

tt 

tt  tt 

“  =6.43. 

118 


PHOTOGRAPHIC  MANIPULATIONS. 


As  an  example,  suppose  it  be  intended  to  build  a  skylight 
fourteen  feet  square,  and  to  give  it  a  pitch  of  15°,  what  perpen¬ 
dicular  elevation  must  be  given  to  the  top  ridge  ? 

Consulting  Table  II.  we  find  for  10  feet  and  angle  of  15°  2.59 

For  the  four  additional  feet  of  the  14  we  add  four-tenths  of 
2.59 . 1.04 

And  find  8T603^  feet,  or  8  feet  7J  inches  nearly  .  .  8.68 

The  form  A,  Fig.  81,  may  be  still  otherwise  varied.  A  “  lean 
to”  roof  may  be  substituted,  that  is,  the  glass  G  may  be  continued 
all  the  way  with  the  same  pitch  till  it  reaches  the  side  wall, 
which  is  then  much  higher,  and  the  roof  R  is  thus  superseded. 

Mr.  Fennemore’s  glass  room  is  arranged  upon  a  different  plan, 
as  will  be  seen  by  the  adjoining  figure.  Its  dimensions  are  : — 

Top  light,  width . 19  feet. 

“  length . 12  44 

Side  light,  width . 12  44 

Greatest  height . 12  44 

Lowest  44  . .  .  7  44 

The  pitch  of  the  top  light  is  five  feet  in  twelve,  or  five  inches 
to  the  foot.  Eeference  to  Table  II.,  p.  117,  will  show  that  this 
corresponds  to  an  angle  of  between  twenty-four  and  twenty-five 
degrees. 

Fig.  86. 


Mr.  Wenderoth’s  skylight  is  in  form  somewhat  like  that  of 
Mr.  Fennemore’s,  that  is,  it  is  A,  Fig.  81,  widened  out.  But  the 
sitter  has  his  back  to  the  west  wall,  and  the  line  from  the  camera 
to  the  sitter  has  the  usual  east  and  west  direction.  He  has,  in 


THE  GLASS  ROOM. 


119 


addition,  arrangements  for  admitting  light  at  the  ends,  and  also 
a  narrow  line  of  opening  just  at  the  top  of  the  south  wall.  This 
last,  without  the  most  careful  management,  must  lead  to  cross 
lights,  and  is  probably  of  no  real  use. 

Sarony  uses  a  longer  joom,  with  glass  at  each  end,  in  order  to 
carry  on  two  sets  of  operations  at  once.  Both  ends  have  light 
from  the  northward.  The  roof-light  is  13  feet  long,  and  13  feet 
along  the  slides  slanting  upwards,  which  have  an  angle  of  thirty 
degrees.  The  side  light  commences  at  a  distance  of  five  feet 
from  the  floor,  and  meets  the  roof  three  feet  above  this ;  it  has 
the  same  length,  thirteen  feet,  as  the  roof-light  that  joins  it.  The 
construction  is,  therefore,  very  similar  to  Fig.  85,  if  we  sup¬ 
pose  another  glazed  portion  added  to  the  farther  end.  The 
height  E  H  is  five  feet,  the  glazed  side  has  a  height  D  E  of  three 
feet.  The  upper  skylight  is  square,  the  lengths,  B  D,  D  K,  being 
each  thirteen  feet.  The  pitch  or  angle  B  D  C  is  thirty  degrees. 
It  is  easy,  by  Table  II.,  p.  117,  to  find  the  perpendicular  height 
of  the  top  of  the  skylight  from  the  floor.  The  table  gives  for  the 
absolute  height,  C  B,  of  the  sash,  6  feet  6  inches,  and  as  D  H  is 
here  8  feet,  the  whole  height,  A  B,  is  14  feet  6  inches. 

Gurney’s  new  studio  is  18x30,  with  a  top  light  15x13,  the 
side  light  15  feet  long  and  7  high,  beginning  at  a  height  of  2J 
feet  from  floor.  The  top  light  is  at  its  junction  with  the  side 
light  9  feet  6  inches  from  floor;  at  its  highest  point  11  feet  8 
inches.  Its  inclination  is,  therefore,  2  feet  2  inches  in  13,  or  2 
inches  to  the  foot.  This  is  1.67  feet  in  10  feet  of  slant  line.  Re¬ 
ferring  to  Table  II.,  p.  117,  we  see  that  this  corresponds  with  an 
inclination  a  little  under  ten  degrees,  or  not  quite  one-third  as 
much  as  that  of  the  last-mentioned  studio. 

In  a  new  studio,  recently  completed,  Loescher  and  Petzch,  of 
Berlin,  continue  to  use  the  ridge  roof  form,  but  built  in  somewhat 
different  proportions  from  their  former  studio,  described  in  the 
first  edition  of  this  manual.  Their  light  fronts  north,  and  the 
skylight  is  protected  from  the  direct  sunlight  by  higher  build¬ 
ings  south  of  it.  The  glass  room  is  35x17 — the  lower  side  of 
the  skylight  is  10  feet  from  the  floor,  the  higher  14,  the  inclina¬ 
tion  is,  therefore,  4  feet  in  17.  The  whole  side  of  the  room,  and 
about  three-quarters  of  the  roof,  are  glazed.  This  plan  involved 
so  great  an  exposure  of  side  light,  that  especial  means  were  found 
necessary  to  exclude  perfectly  all  that  was  not  needed.1 

1  For  fuller  details  and  figures  see  Phila.  Photog.,  1870,  pp.  89  and  117. 


120  PHOTOGRAPHIC  MANIPULATIONS. 

The  particulars  of  the  construction  of  the  glass  room  of  a  cele¬ 
brated  Parisian  photographer,  Reutlinger,  have  been  given  to  the 
public.  On  the  north  side  there  is  a  perpendicular  glazed  por¬ 
tion,  22  feet  long  and  12  high.  The  glass  roof  has  only  14  feet 
of  width,  protected  by  an  awning  controlled  by  pulleys  inside, 
to  cut  off  direct  sunlight.  The  glass  overhead  is  ground  glass, 
and  so  are  the  sides  as  high  as  the  eyes.  The  entire  length  of 
the  room  is  about  44  feet.1 

Salomon,  of  Paris,  uses  a  system  corresponding  for  the  most 
part  with  Pig.  85.  But  as  one  of  his  essential  peculiarities  lies  in 
the  use  of  a  diagonal  background,  a  sketch  of  the  interior  of  his 
glass  room  will  be  given  in  the  section  on  backgrounds. 

Any  one  of  the  forms  of  glass  room  which  have  been  here  par¬ 
ticularly  described,  will,  in  good  hands,  give  good  work.  The 
whole  system  used  by  Loescher  and  Petzch  seems  that  most  in 
accordance  with  sound  principles,  and  without  meaning  in  the 
least  to  detract  from  the  excel]  ence  of  the  others,  is  that  which 
is  most  strongly  recommended  here. 

Whatever  system  is  adopted,  the  following  precautions  will  be 
found  useful :  Keep  the  end  at  which  the  camera  is  placed  dark, 
and  avoid  having  much  illumination  in  the  space  between  the 
camera  and  the  sitter,  because  the  slight  dust  that  always  floats 
in  the  air  of  a  room  reflects  back  a  portion  of  any  light  that  falls 
upon  it,  and  so  takes  from  the  clearness  and  brilliancy  of  the 
work.  As  to  the  power  of  dust  to  do  this,  any  one  may  convince 
himself  by  observing  how  visible  the  path  of  a  sunbeam  in  a 
dark  room  is  rendered  by  the  dust  that  floats  in  the  air,  and  it  is 
a  general  rule  that  whatever  is  capable  of  sending  bach  light  to  the 
eye  will  also  send  it  to  the  camera.  Dust  in  the  glass  room  is  in 
every  respect  a  serious  evil,  and  should  be  carefully  prevented. 

Closely  allied  to  this  principle  is  that  the  direction  of  the  light 
that  is  admitted  should  be  towards  the  sitter  and  not  towards  the 
camera. 

It  cannot  be  expected  that  any  one  system  of  illumination 
should  be  best  for  all  purposes.  Groups  are  best  taken  in  a  well- 
diffused  light,  affording  to  all  parts  an  equable  illumination, 
whereas  for  many  sorts  of  portraits,  such  a  light  is  unmanage¬ 
able  :  in  fact,  many  skilful  operators,  in  making  single  portraits, 
try  to  suppress  all  strong  light  except  that  which  falls  directly 


Photographische  Mittheilungen ,  No.  41,  p.  130. 


THE  GLA.SS  ROOM. 


121 


on  the  head.  Groups  also  are  best  managed  in  a  tolerably  large 
room,  whereas  experience  seems  to  show  that  single  heads  are 
best  taken  in  rather  small  glass  rooms,  and  there  is  no  doubt  that 
in  a  small  room  the  pose  is  more  rapid  than  in  a  large  one ;  light 
becomes  more  diluted  in  a  large  room,  and  the  sitter  is  farther 
from  the  glass. 

Length  of  the  Glass  Room. — This  will  be  determined  by  the 
character  of  the  work  to  be  done.  The  shortest  length  in  which 
a  full-length  card  portrait  can  be  taken  is  21  feet,  full-length 
cabinet  24,  full-length  whole  size  40.  These  requirements  are 
those  that  will  fix  the  length,  because  heads  and  half-lengths  can 
always  be  taken  within  a  shorter  space.  The  breadth  of  the 
room  will  need  to  be  approximately  half  its  length. 

The  quality  of  the  glass  needed  for  the  skylight  has  already 
been  discussed.  As  to  its  management,  it  may  be  either  the 
simple,  clear  glass,  ground  glass,  or  blue  frosted.  Some  persons 
are  under  the  belief  that  the  blue  color  increases  the  actinic 
power  of  the  light.  This  is  a  complete  error  :  any  skylight  will 
work  faster  without  than  with  such  an  application.  The  ad¬ 
vantage  of  the  frosting  lies  in  very  greatly  diminishing  the  glare, 
so  that  a  larger  amount  of  active  light  may  be  admitted  without 
inconveniencing  the  sitter.  Ground  glass  is  little  used  here,  it 
greatly  softens  the  light,  but  also  greatly  diminishes  it  strength. 
It  has  been  found  that  whilst  ordinary  (clean)  glass  holds  back 
but  about  five  per  cent,  of  the  light,  ground  glass  stops  one-half. 
Nevertheless  ground  glass  is  largely  used  in  France,  and  with 
great  success.  The  blue  stippling  is  the  favorite  method  here, 
and  is  extending  to  Germany. 

To  apply  it,  blue  frosting  is  first  brushed  on  with  any  ordinary 
flat  brush.  Then  a  thick  round  painter’s  brush  is  tied  up  with  twine 
to  about  an  inch  of  the  end,  and  is  tapped  against  the  moist 
frosting  until  the  effect  is  obtained. 

Ventilation. — Some  portion  of  the  glass  side  should  be  arranged 
to  slide,  or  there  should  be  somewhere  a  window  that  can  be 
raised.  It  is  true  that  its  use  will  be  somewhat  limited:  the 
photographer  cannot  of  course  run  the  risk  of  having  a  puff  of 
wind  derange  drapery,  and  even  when  opened  between  exposures 
there  is  danger  of  the  introduction  of  dust.  But  in  weather  in 
which  there  is  no  dust  in  the  atmosphere,  it  is  highly  desirable 
to  get  the  benefit  of  the  freshness  of  the  exterior  air.  Nothing 
9 


122 


PHOTOGRAPHIC  MANIPULATIONS. 


tends  more  to  give  a  portrait  an  old  and  faded  expression  than  a 
hot  close  atmosphere,  the  depressing  effects  of  which  are  apt  to 
tell  quickly  upon  the  expression. 

§  3. — Control  of  Sunlight. 

An  important  consideration  presents  itself  with  respect  to  all 
the  forms  of  roof  and  glazing  just  shown  in  section.  Even  if 
the  roof  looks  directly  to  the  north,  it  is  impracticable  to  give  it 
so  high  a  pitch  that  the  sun  shall  not  shine  over  the  ridge  at 
midday,  and  it  must  also  shine  over  the  ends  morning  and  even¬ 
ing,  unless  higher  walls  abut  against  them.  Various  efforts  have 
been  made  by  different  photographers  to  obviate  this  difficulty. 
Some  select  a  position  where  the  walls  of  adjoining  houses  afford 
a  screen,  some  use  awnings  moved  by  pulleys,  others  trust  to 
excluding  the  sun  by  curtains  and  shades  inside.  These,  indeed, 
are  of  course  always  necessary  to  regulate  the  amount  and  direc¬ 
tion  of  light,  independently 
of  direct  sunbeams.  An 
effectual  course,  in  the  ab¬ 
sence  of  protection  from 
other  parts  of  the  build- 
ing,  or  of  adjoining  build¬ 
ings,  is  to  construct  a  frame¬ 
work  of  boards,  as  shown 
in  Eig.  87.  This  is  valu¬ 
able  not  only  as  respects 
light,  but  checks  the  over¬ 
heating  of  the  glass  room. 
The  same  figure  is  intended  to  show  a  system  of  construction 
sometimes  adopted  in  this  city  ;  it  is  easy  to  make  and  cheap,  but 
less  advantageous  than  some  others. 

Some,  however,  trust  so  entirely  to  inside  shades  to  exclude  the 
sun,  as  to  prefer  a  southern  exposure,  softening  the  sunlight  by 
shades,  and  getting  it  under  management  as  best  they  may.  The 
solitary  advantage  that  this  system  possesses  is,  that  in  dull 
weather  the  southern  light  is  stronger  than  the  northern. 

Some,  in  order  to  get  every  variety  of  light,  use  a  ridge  roof, 
with  equal  slopes  north  and  south,  both  glazed,  so  that  the  prin¬ 
cipal  light  may  be  taken  from  either  side,  as  may  be  found  best 
suited  to  the  weather  and  the  sitter.  But  this  has  a  most  serious 


Fig.  87. 


THE  GLASS  ROOM. 


123 


objection  in  tbe  intense  heat  caused  by  it.  The  glass  room  be¬ 
comes  in  hot  weather  a  veritable  hot-house.  The  sitters  suffer — 
the  chemicals  do  not  work  well. 

To  maintain  a  moderate  temperature  in  the  glass  room  is  at 
best  a  difficult  matter,  even  when  not  complicated  by  a  southern 
exposure.  A  brick  wall  on  the  south  side  is  a  great  protection, 
and  there  should  be,  if  possible,  a  space  between  the  southern 
slope  of  the  ridge  and  the  ceiling  on  that  side.  An  excellent 
arrangement  on  all  these  grounds  is  represented  in  Fig.  88.  At 
the  upper  angle  of  the  ceiling  A,  a  girder  supports  a  wooden 
studding  B.  This  allows  an  interspace  D  on  the  south  pitch  of 

Fig.  88.  Fig.  89. 


the  roof — very  effectual  in  diminishing  the  heat.  The  wall  B 
tending  to  keep  off  the  noon  sun  from  the  glazing  A  C. 

It  is  evident  that  if  the  south  wall  supports  a  higher  building 
adjoining,  as  shown  in  Fig.  89,  somewhat  the  same  result  is  at¬ 
tained.  Such  a  form  of  construction  requires  especial  care  to 
render  it  water-tight  at  the  junction  of  the  roof  and  wall.  The 
gutter  in  the  angle  must  have  a  rapid  pitch  from  back  to  front 
(which  cannot  be  shown  in  the  section),  and  must  be  thoroughly 
tinned  by  a  good  workman. 

It  will  be  important  to  keep  the  glass,  especially  its  outer  sur¬ 
face,  clean,  and  an  arrangement  for  scattering  water  over  the 
top  light  will  have  the  double  advantage  of  affording  an  easy 
means  of  washing,  and  a  method  of  cooling  the  room  in  hot 
weather. 

Keeping  the  glass  clean  has  an  importance  even  greater  than 
might  be  supposed.  It  has  been  ascertained  by  careful  trial  that 
the  best  and  newest  colorless  glass  stops  one- twentieth  of  the  light; 


124 


PHOTOGRAPHIC  MANIPULATIONS. 


a  moderate  accumulation  of  dust,  perhaps  spread  and  splashed 
by  ram  and  dew,  may  increase  this  source  of  loss  five  or  tenfold. 


§  4. — Secondary  Lights. 

In  all  these  sections  the  sitter  is  supposed  to  be  at  the  far  end, 
and  looking  towards  the  spectator.  He  will  thus  receive  on  his 
left  side  a  powerful  light  from  the  glass  roof,  whilst  his  right 
side  will  be  comparatively  dark. 

How,  a  difference  in  light  on  the  two  sides  is  desirable,  and 
even  necessary,  but  this  difference  must  not  exceed  a  certain 
moderate  measure.  And  the  dark  side  of  the  face  requires  a 
secondary  light ,  to  give  transparency  to  the .  shadows  upon  it. 
Three  different  methods  are  used  for  this  end. 

First,  and  most  common,  reflectors  are  used.  Generally,  a  large 
screen  covered  with  white  paper,  or  white  cloth,  is  placed  on  the 
side  of  the  sitter,  opposite  the  light.  Some  have  used  screens 
covered  with  silver  paper ;  others,  large  mirrors. 

Secondly,  some  have  opened  a  window  on  the  south  side,  and 
let  in  light  directly  on  the  dark  side. 

Thirdly,  some  object  that  these  methods  give  false  lights,  es¬ 
pecially  affecting  the  expression  of  the  eye,  and,  therefore,  prefer 
to  keep  the  south  side  of  the  room  of  a  sufficiently  light  color  to 
throw  back  a  volume  of  soft  white  light,  adequate  to  light  up 
the  shadows. 

The  brilliancy  of  the  picture  is  always  aided  by  excluding  all 
extraneous  light.  The  camera,  therefore,  should  always  be  under 
an  unglazed  portion  of  the  roof,  and  screens  should  be  so  ar¬ 
ranged  that,  if  the  eye  be  placed  where  the  lens  is  to  be,  it  shall 
see  no  uncurtained  glass.  Too  much  glass  is  very  objectionable, 
especially  toward  the  direction  of  the  camera.  The  air  of  a  room 
always  contains  dust.  The  more  strongly  the  dust  between  the 
sitter  and  the  lens  is  illuminated,  the  more  it  will  affect  the  pic¬ 
ture,  and  always  by  taking  from  its  brilliancy. 

The  Tunnel  System,  is  not  to  be  recommended,  though  it  is 
certain  that  good  work  has  been  done  in  this  form  of  house,  still 
the  system  is  every  way  inferior  to  the  ridge  roof.  In  it,  one 
end  of  the  room,  that  in  which  the  camera  is  placed,  is  lower  than 
the  other,  and  the  vertical  ‘space  between  the  two  ceilings  is 
glazed.  Thus  the  strongest  light  is  full  in  the  sitter’s  eyes,  at 


THE  GLASS  ROOM. 


125 


the  same  time  that  its  quantity  is  almost  always  deficient,  seri¬ 
ously  incommoding  the  operator  in  dull  weather,  and  producing 
effects  inferior  to  the  ridge  roof,  in  good. 

It  has  been  said  that  few  photographers  succeed  in  their  first 
attempts  at  building  a  glass  house ;  that  they  require  the  expe¬ 
rience  of  a  first  failure  to  attain  subsequent  success.  Failures  of 
this  kind  are  expensive,  and  infinitely  vexatious.  They  are  best 
avoided  by  obtaining  beforehand  a  clear  conception  of  what  are 
the  conditions  essential  to  success,  and  then  carefully  and  thought¬ 
fully  applying  them  to  the  position  which  their  glass  room  is  to 
occupy.  Sometimes  splendid  success  comes  by  mere  chance. 
Mr.  Hughes  gives  an  instance  in  which  the  portraits  produced 
by  a  photographer  in  a  country  town  in  England  were  so  excel¬ 
lent  as  to  induce  him  to  travel  a  long  distance  to  see  the  maker. 
He  proved  to  be  a  man  of  limited  intelligence,  who,  however, 
had  chanced  to  erect  an  excellent  room,  where  an  abundance  of 
soft,  pure  light  from  the  north  was  received  to  the  exclusion  of 
cross  lights.  The  photographer  knew  that  his  work  was  excel¬ 
lent,  and  ascribed  it  all  to  his  personal  skill,  neither  understand¬ 
ing  nor  appreciating  the  merits  of  his  room.  Encouraged  by 
success,  he  erected  a  new  gallery  in  another  town,  intended  to  be 
far  better  than  his  old  one,  but  was  confounded  to  find  that  in  it 
he  could  not  make  anything  worth  having. 

One  material  difference  that  will  be  found  between  a  well  and 
ill -planned  glass  room  is,  that  in  the  former  work  can  be  con¬ 
tinued  till  a  late  hour  in  the  afternoon,  and,  even  then,  brilliant 
and  well-modelled  portraits  can  be  got.  It  is,  therefore  (and  this 
cannot  be  too  clearly  understood),  no  proof  of  a  good  construction 
that  the  operator  can  show  a  piece  of  first-rate  work  made  in  it.  A 
glass  room  can  hardly  be  so  badly  planned  but  that  in  some  sort 
of  weather,  and  at  some  hour  of  the  day,  good  work,  may  be  done 
in  it.  The  well-planned  room  is  one  that  is  always  in  a  condition 
to  meet  the  operator’s  needs. 


126 


PHOTOGRAPHIC  MANIPULATIONS. 


CHAPTER  III. 

PYROXYLINE  AND  COLLODION. 

\  1. — Pyroxyline. 

The  manufacture  of  this  substance  has  passed  so  much,  in  fact, 
so  completely  into  the  hands  of  those  who  make  it  their  business, 
and  who  employ  special  methods,  that  it  scarcely  requires  atten¬ 
tion  here,  except  in  a  brief  way. 

When  any  form  of  cellulose,  such  as  cotton,  paper,  linen,  &c., 
is  exposed  to  the  action  of  mixed  nitric  and  sulphuric  acid,  a 
substitution  takes  place  by  which  one  or  more  molecules  of  N04, 
hyponitric  acid,  are  taken  up  by  the  cellulose.  Several  different 
compounds  are  thus  formed,  and  often  simultaneously.  When 
the  acid  mixture  is  too  weak,  the  cellulose  is  dissolved  with 
abundant  disengagement  of  red  fumes.  When  it  is  somewhat 
stronger,  and  used  before  the  heat  generated  by  the  mixture  of 
the  acids  escapes,  pyroxy lines  suitable  fo,r  photography  are  pro¬ 
duced,  thoroughly  soluble  in  mixed  alcohol  and  ether.  With 
lower  temperatures  and  stronger  acids,  the  more  explosive  form 
of  pyroxline  is  produced,  which  does  not  dissolve  well  in  the 
usual  solvents. 

The  proportions  most  commonly  employed  in  these  later  years, 
are  to  take  equal  bulks  of  the  two  acids,  using  sulphuric  acid  of 
full  commercial  strength  (1.83  to  1.84),  and  nitric  acid,  sp.  gr. 
1.42.  For  each  ounce  of  cotton,  about  twelve  fluidounces1  of 
each  acid  will  be  required.  When  this  relative  proportion  of 
acids  is  varied  from,  it  is  more  usual  to  increase  the  sulphuric 
acid  than  the  nitric.  The  proportion  of  12  sulphuric  to  10  nitric 
is  often  used,  and  indeed  the  sulphuric  may  be  increased  until  it 

1  As  it  is  more  convenient  to  measure  liquids  than  to  weigh  them,  it  is  com¬ 
mon  to  take  them  in  “fluidounces” — that  is,  a  quantity  equal  to  a  measured 
ounce  of  water.  Of  course,  with  heavy  acids,  the  quantity  may  largely  exceed 
an  ounce  in  weight.  A  fluidounce  of  sulphuric  acid  will  weigh  not  far  short 
of  two  ounces,  one  of  nitric  acid  1.42,  nearly  an  ounce  and  a  half.  So  in  collo¬ 
dion  formulae  the  ounce  of  alcohol  or  ether  means  always  a  measured  ounce, 
and  consequently  much  less  than  an  ounce  in  weight. 


PYROXYLINE  AND  COLLODION. 


127 


is  threefold  the  bulk  of  the  nitric.  Some  hold  that  this  excess 
of  sulphuric  acid  tends  to  increase  the  intensity  of  the  pyroxyline 
produced.  The  mixing  of  the  acids  produces  considerable  heat. 
If  the  thermometer  plunged  into  them  rises  above  150°,  the  mix¬ 
ture  is  allowed  to  cool ;  if  it  stands  below,  heat  is  applied.  When 
the  temperature  is  right  the  cotton  is  immersed  in  tufts,  is  pushed 
quickly  under  the  liquid  so  as  to  become  soaked  immediately 
(otherwise  red  fumes  may  burst  out  from  it,  which,  however,  will 
be  checked  by  a  complete  immersion).  The  whole  cotton  is  got 
in  as  rapidly  as  possible,  and  is  well  worked  round  to  insure 
equality  of  action.  After  eight  or  ten  minutes  of  immersion,  the 
cotton  is  drawn  up  with  two  stout  glass  rods,  pressed  against  the 
sides,  and  then  thrown  into  a  bucket  of  water.  Without  a  mo¬ 
ment’s  delay  the  operator  separates  it  out  so  that  the  water  may 
penetrate  it  instantly.  This  can  only  be  well  done  with  the 
fingers,  and  as  they  would  be  corroded  and  stained  yellow  by  the 
acids,  it  is  best  to  use  India-rubber  gloves. 

The  pyroxyline  then  receives  a  very  thorough  washing  in  run¬ 
ning  water,  is  squeezed  out  and  dried  at  ordinary  temperatures 
and  not  near  a  stove  or  other  source  of  heat.  The  washing  must 
be  sufficient  to  remove  every  trace  of  acid.  Some,  therefore, 
wash  it  with  very  dilute  ammonia  or  solution  of  carbonate  of 
soda,  one  ounce  to  the  gallon,  which  must  itself  be  washed  out 
of  the  cotton  with  clean  water. 

As  commercial  nitric  acid  varies  very  much  in  strength,  it  is 
often  found  convenient  to  substitute  nitrate  of  potash,  and  to 
increase  the  quantity  of  sulphuric  acid,  inasmuch  as  part  goes  to 
separate  the  nitric  acid  from  the  potash.  It  is  also  affirmed  that 
pyroxyline  made  with  nitrate  of  potash  dissolves  more  easily, 
and  gives  a  clearer  solution,  than  that  made  with  nitric  acid. 

Mix  200  parts  of  sulphuric  acid  of  1.84  (the  full  commercial 
strength)  with  100  parts  of  dried  and  pulverized  nitrate  of  potash, 
and  keep  them  at  a  temperature  of  147°  to  150°  F.,  which  must 
be  maintained  during  the  operation.  Stir  with  a  glass  rod  till 
the  lumps  disappear.  Then  add  six  to  eight  parts  of  perfectly  dry 
carded  cotton.  Agitate  the  mixture  from  time  to  time  with  a 
glass  rod.  After  the  action  has  continued  for  from  ten  to  forty- 
five  minutes,  empty  suddenly  into  a  large  pan  of  water.  Wash 
thoroughly  and  rapidly  with  plenty  of  water ;  finally  with  boil¬ 
ing  distilled  water. 

During  the  whole  operation  the  temperature  must  remain  over 


128  PHOTOGRAPHIC  MANIPULATIONS. 

147°  or  the  pyroxyline  is  of  inferior  quality,  and  if  over  160° 
the  cotton  is  partly  dissolved,  and  becomes  shorter  in  fibre.1 

But,  as  already  said,  the  manufacture  of  pyroxyline  as  a  busi¬ 
ness  is  now  so  thoroughly  understood,  that  it  is  no  longer  neces¬ 
sary  for  the  photographer  to  prepare  it  for  himself  in  order  to 
have  it  good.  On  the  contrary,  it  is  probable  that  it  would  cost 
him  much  labor  and  some  experience,  to  get  it  of  as  good  quality 
as  that  which  he  can  readily  purchase. 

It  has  been  found  that  the  quality  of  the  original  cotton  used 
has  much  to  do  with  the  resulting  pyroxyline,  and  that  in  general 
the  best  cottons  make  the  best  pyroxyline — especially  the  Ameri¬ 
can  Sea-Island.  Also,  that  different  cottons  require  different 
treatment ;  the  same  mixtures  of  nitric  and  sulphuric  acids,  or  of 
nitre  and  sulphuric  acid,  which  give  the  best  results  with  one 
description  of  cotton,  will  give  inferior  results,  or  perhaps  fail, 
with  another.  It  seems  to  be  well  attested  that  a  small  quantity 
of  chlorine  in  the  nitric  acid  adds  considerably  to  the  intensity  of 
the  cotton,  but  diminishes  its  adhesiveness  to  the  glass.  The 
writer  has  observed  that  the  introduction  of  a  chloride  into  the 
collodion  is  attended  with  the  same  results,  increased  strength  in 
the  picture,  accompanied  with  a  tendency  of  the  film  to  slip  from 
the  plate. 

As  to  the  keeping  properties  of  pyroxyline,  especially  at  tem¬ 
peratures  above  the  common,  there  exists  a  great  difference  of 
opinion.  It  has  been  affirmed  that  pyroxyline  exposed  for  several 
days  to  a  temperature  of  150°  F.  became  uniformly  decomposed, 
and  that  at  the  temperature  of  boiling  water,  some  specimens 
explode.  On  the  other  hand,  another  experimenter  declares,  that 
pyroxyline  was  sealed  up  in  a  glass  bottle  and  exposed  in  his 
garden  for  a  year,  the  temperature  of  the  interior  of  .  the  bottle 
having  frequently  exceeded  150°  F.,  and  was  found  at  the  expira¬ 
tion  of  the  time  to  be  unaltered. 

That  pyroxyline  does  easily  decompose  there  can  be  no  doubt. 
And,  also,  that  that  decomposition  is  greatly  aided  by  light — 
even  by  diffuse  light.  The  writer  prepared  at  one  time  several 
different  pyroxylines,  which  were  placed  in  glass  bottles  and 
corked.  One  of  these  bottles  was  partly  used  just  before  leaving 
town  for  the  summer,  and  was  by  oversight  left  on  the  table, 
where  it  remained  for  nearly  three  months.  The  room  received 


1  Belitzky,  Br.  J.  XII.,  4. 


PYROXYLINE  AND  COLLODION. 


129 


a  north  light  only,  and  no  sunlight.  At  the  expiration  of  the 
time  just  mentioned,  the  pyroxyline  was  converted  into  a  moist, 
sticky,  spongy  substance,  not  one-fifth  the  bulk  of  the  original 
cotton;  the  vial  was  filled  with  red  vapors  of  hyponitric  acid, 
and  the  cork  much  eaten  away.  Other  bottles  left  in  a  closed 
closet  had  not  suffered. 

For  this  reason  pyroxyline  should  always  be  kept  in  opaque 
cases.  It  is  also  found  that  it  keeps  better  when  not  too  closely 
kept  from  the  air.  Pasteboard  boxes  are  the  most  suitable,  and 
the  most  usually  employed. 

M.  Blondeau  has  published  some  interesting  views  on  the 
subject  of  pyroxylines,  which  may  be  briefly  expressed  as 
follows  : — • 

He  considers  pyroxyline  to  be  a  definite  compound  of  fulmi¬ 
nose ,  a  substance  isomeric  with  cellulose,  and  nitric  acid.  Of  this 
fulminose  little  is  stated  except  that  it  is  decomposed  at  140°  F. 
into  vapor  of  water  and  carbon.  In  the  case  of  pyroxyline,  the 
nitric  acid  which  is  in  combination  with  the  fulminose  oxidizes 
the  carbon  to  carbonic  oxide,  so  that  the  products  of  explosion 
are  carbonic  oxide,  nitrogen,  and  vapor  of  water. 

M.  Camuzat  affirms  that  when  collodion  is  poured  into  water  it 
separates  into  three  portions,  a  powder  which  sinks,  a  flaky 
portion  that  swims,  and  a  third,  which  dissolves.  In  his  opinion, 
the  flaky  portion  is  the  only  one  which  is  essential  or  useful  in 
photography.  It  seems  almost  certain,  however,  that  the  nature 
of  the  image  must  depend  also  upon  any  soluble  organic  matter 
present.  In  one  hundred  parts  he  found — 


Flaky  part. 

Powdery  part. 

Soluble  part. 

Best  cotton 

. 

. 

31 

15 

54 

Ordinary 

. 

. 

27 

13 

60 

Powdery 

. 

. 

27 

7 

66 

Papyroxyl 

. 

60 

5 

35 

Dr.  Leisegang  strongly  recommends  the  substitution  of  tissue 
paper  for  cotton  in  preparing  pyroxyline.  The  tissue  paper  is 
cut  into  strips  and  plunged  into  the  acid  mixture,  which  per¬ 
meates  it  more  rapidly  and  evenly.  There  is,  therefore,  less 
tendency  to  decomposition,  and,  it  is  affirmed,  the  product  is 
more*  regular  and  uniform  in  its  character.  It  is  also  claimed 
that  it  gives  a  remarkably  smooth  and  uniform  film  when  poured 
out  upon  the  glass.  Of  this  papyroxyline  4  to  5  grains  only  are 
dissolved  in  the  ounce  of  solvent. 


130 


PHOTOGRAPHIC  MANIPULATIONS. 


A  variety  of  pyroxyline,  called  “  alcoholic,”  has  been  intro¬ 
duced,  but  has  been  found  of  little  use,  even  in  our  hottest  sum¬ 
mer  weather,  with  the  thermometer  ranging  from  90°  to  100°. 
The  ordinary  pyroxylines,  made  up  with  perhaps  a  little  more 
alcohol  than  in  cooler  weather,  are  preferred. 

Xyloidine  is  a  substance  analogous  to  pyroxyline,  produced  by 
the  same  mixed  acids,  when  made  to  act  upon  starch.  It  dries 
from  its  solutions  as  a  dead ,  and  not  as  a  transparent  film.  Nitro- 
glucose  will  be  discussdd  in  Chapter  XII. 

The  careful  study  which  every  department  of  photography  has 
received  during  the  past  years  has  taught  us  the  almost  unlimited 
influence  exercised  upon  photographic  operations  by  the  nature 
of  the  pyroxyline  used.  And  especially  that  this  affects  the  image 
obtained  even  more  than  the  salts  dissolved  in  the  collodion.  So 
that  it  is  impossible  to  say  that  any  particular  salting  is  best  for 
any  particular  photographic  process.  All  we  can  say  is,  that  a 
particular  salting  does  best  with  some  particular  pyroxyline. 

It  has  not  been  found  practicable  in  cottons  made  for  the  wet 
process,  to  combine  great  sensitiveness  and  great  intensity.  The 
most  sensitive  cottons  mostly  give  rather  thin  soft  images,  de¬ 
ficient  in  intensity,  needing  re-development,  whilst  those  that 
give  easily  a  full  and  bold  image  need  a  longer  exposure. 

These  tendencies  of  the  cotton  necessarily  affect  the  salting. 
A  very  intense  cotton  will  do  best  with  a  good  deal  of  bromide, 
a  treatment  very  inappropriate  for  one  tending  to  give  a  thin 
soft  image. 

Nothing  but  actual  trial  will  determine  the  quality  of  a  cotton  : 
the  indications  which  some  rely  on  are  mostly  fallacious.  A 
yellowish  color  has  been  supposed  to  indicate  intensity,  but  in 
reality  depends  upon  the  wash  water  having  contained  traces  of 
muddiness.  Some  think  that  a  short  fibre  indicates  intensity  ; 
this  is  likewise  a  mistake,  as  is  the  supposition  that  a  powdery 
cotton  is  intense.  These  indications  may,  or  may  not,  accompany 
intensity. 

Nor  can  manufacturers  produce  at  will,  with  any  exactness, 
any  particular  quality  of  cotton,  or  even  re-produce  one  that 
they  have  already  made.  The  best  that  they  can  do  is  to  avoid 
any  wide  variation. 


PYROXYLINE  AND  COLLODION. 


131 


§  2. — Collodion. 

When  pyroxyline  is  dissolved  in  acetic  ether,  it  makes  a  per¬ 
fect  solution,  but  dries  opaque.  The  solution  of  good  negative 
cotton  in  a  mixture  of  alcohol  and  ether  has  the  inestimable 
quality  of  leaving  behind  it  in  drying  an  absolutely  transparent 
film,  not  to  be  distinguished  from  the  glass  on  which  it  lies.1  It 
is,  moreover,  acted  npon  in  some  way  by  nitrate  of  silver,  with 
the  effect  of  adding  greatly  to  the  ordinary  sensibility  of  iodide 
and  bromide  of  silver,  so  that  in  the  “  wet  collodion  process”  a 
fraction  of  a  second  is  sufficient,  under  favorable  circumstances, 
to  impress  a  latent  image,  full  of  gradation  and  detail,  in  the 
camera. 

Formerly,  the  plain  collodion  was  generally  prepared  sepa¬ 
rately,  the  salts  were  dissolved  apart  in  a  portion  of  the  alcohol, 
and  added  subsequently.  But  as  more  care  was  taken  in  the 
manufacture  of  pure  materials,,  and  as  the  proper  constitution  of 
collodions  came  to  be  better  understood,  it  became  possible  to 
prepare  them  so  much  more  stable,  that  now  it  is  more  usual  to 
prepare  at  once  the  collodion  in  the  condition  in  which  it  is  to  be 
used.  A  good  sound  collodion,  placed  in  a  cool  cellar,  will  keep 
two  years,  and  is  then  by  many  preferred  to  fresh. 

Influence  of  Alcohol ,  Ether ,  and  Water  on  Collodion. — Alcohol 
and  ether  have  been  used  in  very  different  proportions  in  collo¬ 
dion.  Water  is  present  in  quantity  depending  upon  the  strength 
or  weakness  of  the  other  two  substances. 

The  tendency  of  ether  is  to  make  a  close,  skinny,  and  tough 
film.  Therefore,  where  it  is  intended  to  transfer  a  film,  it  is  use¬ 
ful  to  employ  a  collodion  with  an  abundance  of  ether. 

Alcohol  loosens  the  film  and  renders  it  porous.  By  rendering 
the  permeation  of  the  developer  easy,  the  development  is  more 
rapid,  and  intensity  is  gained. 

The  action  of  water,  or  in  other  words,  of  alcohol  and  ether  of 
low  grade,  is  mostly  injurious,  except  that  when  there  is  much 
tendency  to  make  silver  stains,  water  in  the  collodion  seems  to 
check  them.  With  too  much  water  there  is  a  tendency  to  crapy 
lines,  to  form  ridges,  and  especially  to  make  a  peculiar  mottled 
appearance  at  the  corner  at  which  the  collodion  is  poured  off. 

1  Some  varieties  leave  a  “dead”  film,  which  is  rendered  transparent  in  the 
varnishing,  and  this  is  by  some  operators  preferred.  It  is  doubtful  if  such  a 
film  is  as  strong  as  a  clear  one. 


132 


PHOTOGRAPHIC  MANIPULATIONS. 


Proportions. — Formerly  ether  was  used  to  excess,  about  3  parts 
ether  to  2  of  alcohol.  For  some  time  past  the  practice  of  em¬ 
ploying  equal  parts  of  each  has  gained  ground. 

Washing  with ,  or  steeping  in,  Alkalies. — Pyroxyline  is  often 
treated  with  ammonia,  which  has  the  effect  of  destroying  any 
acid  that  may  either  have  been  left  in  it  by  the  maker,  or  have 
been  generated  by  a  disposition  to  decompose.  A  more  regular 
action  is  thereby  obtained,  and  a  certainty  of  avoiding  the  in¬ 
sensitiveness  which  acidity  of  the  cotton  inevitably  causes. 

The  ammonia  treatment  is  applied  by  diluting  ordinary  liquid 
ammonia  with  four  times  its  bulk  of  water.  Into  this  the  cotton 
is  plunged,  and  the  solution  well  worked  through  it  by  alternate 
soaking  and  squeezing.  The  cotton  is  then  to  be  well  washed, 
squeezed,  and  dried,  at  ordinary  temperature,  or  by  a  furnace 
flue,  but  not  near  a  stove  or  open  fire. 

It  is  desirable  that  the  drying  should  be  complete  to  avoid  in¬ 
troducing  water  into  the  collodion.  The  plan  used  by  some  of 
getting  the  cotton  ready  at  once  by  moistening  with  alcohol, 
squeezing  out,  and  repeating  this  several  times,  is  not  to  be  re¬ 
commended,  partly  because  the  water  is  not  thus  completely  re¬ 
moved  as  supposed,  but  principally  because  some  sorts  of  cotton 
are  somewhat  soluble  in  alcohol.  The  writer  has  himself  seen 
alcohol  that  has  been  used  for  this  purpose  gelatinize  in  drying, 
so  much  cotton  had  been  taken  up  by  it. 

The  proportion  of  pyroxyline  to  that  of  solvent  varies,  accord¬ 
ing  to  the  character  of  the  pyroxyline  itself,  from  4  to  8  grains; 
5  to  6  is  the  most  usual  with  average  pyroxylines.  Some  cottons, 
however,  make  a  collodion  so  dense  that  the  proportion  must  be 
lessened ;  others  make  it  so  thin  that  6  grains  are  insufficient. 
Something  will  depend  upon  the  character  of  the  work  to  be 
done — for  instance,  negatives  require  a  denser  collodion  than 
positives  (ambrotypes). 

Relation  of  Sailing  to  Development. — The  very  important  influ¬ 
ence  exerted  by  the  nature  of  the  pyroxyline  has  been  already 
dwelt  on.  The  tendency  of  photographers  at  the  present  day  is 
not  to  accept  pyroxylines  on  the  authority  of  the  makers,  but  to 
try  specimens  and  see  what  can  be  done  with  them,  before  mix¬ 
ing  quantities  of  collodion  with  which  it  may  prove  impracti¬ 
cable  to  get  the  very  best  results. 

It  consequently  becomes  important  with  any  particular  cotton 
to  ascertain  exactly  what  it  will  do,  and  this  cannot  be  found  by 


PYROXYLINE  AND  COLLODION. 


133 


mixing  it  according  to  any  routine  formula  to  be  followed  by  a 
routine  development:  this  will  only  ascertain  the  suitableness  of 
the  cotton  for  such  treatment,  and  not  its  real  value. 

The  question  is  not  to  find  a  routine  formula,  but  what  salting 
will  do  best  with  the  particular  specimen.  Some  will  yield  with 
J  grain  of  bromide  as  much  softness  and  detail  as  others  with  2  J. 
It  is  a  good  plan  to  make  up  a  new  sample  in  several  portions, 
with  varying  quantities  of  bromide,  until  that  which  is  best  has 
been  determined.  And  then  having  found  the  best  salting,  we 
must  depend  upon  a  proper  development  to  get  the  best  combina¬ 
tion  of  half-tone  and  intensity. 

A  collodion  giving  a  very  weak  image  with  plenty  of  detail  is 
generally  very  sensitive,  and  will  bear  a  very  weak  developer 
which  deposits  silver  slowly  and  heightens  contrasts,  especially 
if  the  plate  is  kept  in  motion  during  development.  This  will 
be  the  proper  treatment  for  a  collodion  tending  to  give  weak 
negatives. 

A  collodion  giving  strong  contrasts  should  have  a  strong  de¬ 
veloper  which  (as  the  writer  long  since  pointed  out)  tends  to 
soften  the  picture  by  a  more  equal  deposit  of  silver.  This  action 
may  be  heightened  by  using  so  much  developer  as  to  wash  off 
the  plate  a  certain  portion  of  the  bath  solution  with  which  it  is 
soaked. 

Although  a  developer  of  15  to  30  grains  of  sulphate  of  iron 
to  the  ounce  will  do  very  well  for  regular  use  and  suit  most  cases, 
it  will  be  a  great  mistake  to  assume  that  it  will  suit  all  collo¬ 
dions,  or  to  persist  in  using  it  when  the  character  of  the  image 
indicates  the  need  of  a  different  treatment.  To  avoid  the  trouble 
of  keeping  many  developers  on  hand,  one  may  keep  besides  the 
regular  mixture,  one  of  double  strength.  When  a  stronger  de¬ 
velopment  is  called  for,  part  of  this  may  be  added,  or  when  a 
weaker,  the  regular  developer  may  be  diluted  with  water,  and 
must  at  the  same  time  have  an  addition  of  acetic  acid  propor¬ 
tionate  to  the  water  added. 

The  object  of  the  worker  with  the  wet  process  will  always  be 
to  secure  a  very  sensitive  collodion  with  a  reasonable  amount, 
but  not  an  excess,  of  intensity,  and  having  found  a  cotton  which 
with  some  appropriate  salting,  will  answer  this  need,  he  will 
regulate  the  development  so  as  to  make  up  for  whatever  defi¬ 
ciencies  the  character  of  his  images  may  tend  to  show. 


134 


PHOTOGRAPHIC  MANIPULATIONS. 


§  3. — Selection  of  Bases. 

The  selection  of  bases  to  which  the  iodine  and  bromine  shall 
be  united,  is  a  matter  of  very  great  interest  to  the  photographer. 
And  this  has  been  so  well  recognized  that  even  exaggerated  im¬ 
portance  has  been  ascribed  to  it.  The  following  will,  it  is  be¬ 
lieved,  be  found  to  be  the  sum  of  what  is  actually  known  on  the 
subject. 

It  appears  that  the  most  permanent  collodions  are  obtained 
when  the  iodine  and  bromine  are  combined  with  only  a  mode¬ 
rately  powerful  base.  The  alkalies  tend  to  provoke  decompo¬ 
sition,  perhaps  by  attacking  the  hyponitric  acid  contained  in  the 
pyroxyline,  whereby  iodine  is  liberated,  or  at  least  enters  into 
other  forms  of  combination.  Of  the  moderately  strong  bases, 
cadmium  has  been  found  to  give  such  excellent  results  that  it  is 
very  extensively  used. 

On  the  other  hand,  freshly-mixed  collodion  does  not  give  as 
good  results  as  that  in  which  certain  reactions,  little  understood 
as  yet,  have  taken  place  between  the  constituents;  and  these  re¬ 
actions  take  place  much  more  rapidly  when  an  alkaline  base  is 
present.  For  this  purpose  ammonia  is  greatly  preferred.  Po¬ 
tassium  is  liable  to  the  objection  that  its  bromide  is  comparatively 
insoluble  in  the  mixture  of  alcohol  and  ether  used  as  a  solvent. 
And  even  if  the  potassium  appears  in  the  form  of  iodide,  yet  as 
a  bromide  must  be  employed  also,  it  follows,  according  to  the 
well-known  chemical  law,  that  if  the  constituents  present  are 
capable  of  forming  a  combination  insoluble  in  the  solvent  used, 
that  combination  will  be  formed.  Therefore,  if  with  bromide  of 
cadmium  we  mix  iodide  of  potassium  in  such  proportion  that  if 
by  the  combination  of  all  the  potassium  with  its  proportional 
amount  of  bromine,  there  will  be  more  bromide  than  the  liquid 
present  can  dissolve,  then  that  excess  will  inevitably  be  formed 
and  precipitated. 

A  grain,  or  possibly  two,  to  the  ounce  of  bromide  of  potas¬ 
sium  can,  however,  be  kept  in  solution  in  an  ordinary  collodion. 
To  get  it  dissolved,  all  the  salts  should  be  placed  together  in  a 
large  test-tube  or  a  flask,  alcohol  be  poured  over  them,  and  the 
whole  boiled  for  some  minutes.  Fresh  alcohol  is  then  to  be 
added  to  the  undissolved  part,  and  the  operation  repeated  till 
complete  solution  is  effected.  It  should  be  clearly  understood 
that  the  bromides  of  potassium  and  ammonia  are  more  soluble  in 


PYROXYLINE  AND  COLLODION. 


185 


a  solution  of  bromide  or  of  iodide  of  cadmium  than  in  plain 
alcohol.  They  form  double  salts  of  greater  solubility  than  the 
unmixed  alkaline  bromide.  This  fact  explains  why  some  ope¬ 
rators  can  prepare  a  collodion  partly  with  potassium,  and  some 
cannot :  all  depends  upon  the  manner  of  operating. 

Much  also  depends  upon  the  solvents.  The  less  high  the 
grades  of  the  ether  and  alcohol,  the  more  easily  will  the  bromide 
of  potassium  be  kept  in  solution.  The  writer  is  much  disposed 
to  think  that  when  two  grains  of  this  salt  are  used  to  the  ounce 
of  good  solvents,  a  portion  of  it  is  sooner  or  later  precipitated, 
and  if  the  collodion  be  used  whilst  this  precipitate  is  tending  to 
form,  pin-holes  will  result. 

Sodium  forms  a  more  soluble  bromide  than  potassium,  and  the 
use  of  bromide  of  sodium,  or  of  iodide  of  sodium,  in  the  presence 
of  bromide  of  cadmium,  has  been  highly  praised,  but  has  never 
attained  general  acceptance. 

Lithium  forms  a  very  soluble  bromide,  and  its  use  in  collodion 
has  been  very  highly  spoken  of.  Its  higher  price  prevents  its 
being  more  extensively  used.  Its  action  is  similar  to  that  of 
potassium. 

A  curious  difference  exists  between  the  actions  of  alkaline  salts 
and  of  cadmium  compounds  in  this :  that  the  alkaline  iodides 
and  the  bromides  tend  to  render  collodion  thin  and  fluid,  whilst 
the  corresponding  cadmium  compounds  render  it  thick  and 
viscid. 

For  the  various  reasons  here  given,  it  is  almost  invariably 
customary  to  combine  in  collodion  and  alkaline  and  a  metallic 
base. 

Collodions  made  for  sale  must  have  good  keeping  properties, 
therefore  in  such  the  proportion  of  cadmium  largely  prepon¬ 
derates.  Those  mixed  by  photographers  for  their  own  imme¬ 
diate  use,  bear  a  larger  proportion  of  ammonia,  and  this  compo¬ 
sition  is  generally  preferred  by  portraitists. 

Before  touching  upon  the  influence  of  iodine  and  bromine, 
which  will  form  the  subject  of  the  next  section,  I  must  remark 
here  that  it  is  by  no  means  indifferent  in  what  form  we  add  the 
respective  substances  to  the  collodion.  It  is  a  general  law  in 
chemistry,  that  when  different  salts  are  all  completely  dissolved 
in  a  solvent,  the  resulting  combination  will  be  independent  of  the 
form  in  which  the  substances  were  added.  For  example,  if  an 
equivalent  of  nitrate  of  potassium  and  one  of  chloride  of  sodium 


136 


PHOTOGRAPHIC  MANIPULATION'S. 


be  dissolved  in  water,  the  result  will  be  absolutely  the  same  as  if 
one  equivalent  of  chloride  of  potassium  and  one  of  nitrate  of 
sodium  had  been  used.  In  each  case  the  affinities  are  independ¬ 
ent  of  the  original  form  of  the  compounds. 

It  would  be  a  great  mistake  to  apply  this  principle  to  the 
preparation  of  collodion,  as  some  might  be  disposed  to  do.  The 
admixture  of  one  equivalent  of  iodide  of  ammonium  and  one  of 
bromide  of  cadmium  would  produce  a  quite  different  collodion 
from  that  afforded  by  the  mixture  of  one  equivalent  of  bromide 
of  ammonium  and  one  of  iodide  of  cadmium.  This  is  a  point 
that  cannot  be  too  well  understood. 

The  explanation  is,  that  bromide  of  ammonium  is  a  very  stable 
salt,  so,  likewise,  are  bromide  and  iodide  of  cadmium :  but  iodide 
of  ammonium  is  not.  As  received  from  the  manufacturer  it  is 
apt  to  be  yellowish,  and  to  have  a  penetrating  smell,  apparently 
of  iodine.  It  reacts  quickly  on  the  collodion  and  brings  it  soon 
to  an  orange  shade,  as  is  observable  in  collodions  made  with 
iodide  of  ammonium  and  iodide  and  bromide  of  cadmium.  Whereas 
collodions  made  with  bromide  of  ammonium  and  iodide  of  cad¬ 
mium  retain  a  pale  straw-yellow  color  (if  the  pyroxyline  has 
been  quite  neutral)  easily  for  a  year,  and  even  more. 

Mr.  Blanchard  has  published  some  remarkable  experiments 
which  show  the  difference  of  the  action  of  alkaline  and  metallic 
bases.  He  found  that  in  some  cases  a  bath  rendered  alkaline  and 
exposed  to  the  sun,  fogged,  and  that  acidifying  only  made  it 
worse.  If  such  a  bath,  showing  a  decided  alkaline  reaction,  was 
used  to  sensitize  a  film  in  which  ammonium  salts  predominated, 
each  plate  showed  less  fog,  until  presently  perfectly  clean  ones 
were  obtained.  Under  the  same  circumstances,  cadmium  collo¬ 
dions  gave  dense  fog,  without  a  trace  of  an  image. 

This  probably  has  something  to  do  with  the  fact  that  the  ten¬ 
dency  of  late  years  has  been  to  use  less  and  less  cadmium,  some 
even  omitting  it  entirely  (see  formula  5). 

To  resume,  then.  For  all  practical  purposes,  ammonium  and 
cadmium  are  the  great  resources  of  photography  as  bases.  Where 
the  bromine  is  combined  with  the  ammonium,  and  especially 
when  the  proportion  of  ammonium  compound  is  not  over  the 
fourth  parts  of  that  of  the  cadmium,  a  collodion  is  obtained  which 
ripens  within  ten  days  or  a  fortnight,  and  then  continues  of  excel¬ 
lent  quality  for  many  months,  or,  in  a  cool  place,  for  years. 


PYROXYLINE  AND  COLLODION. 


137 


When  the  iodine  is  combined  with  the  ammonium,  and  espe¬ 
cially  when  this  is  used  in  larger  proportions  than  above  men¬ 
tioned,  collodions  are  obtained  that  ripen  rapidly,  and  are  fit  for 
use  in  two  or  three  days,  or  even  in  a  few  hours ;  but  which 
become  dark  colored  and  insensitive,  and  give  harsh  pictures 
when  kept.  Whilst  these  are  in  their  best  condition,  they  are 
by  some  considered  as  giving  the  best  possible  results,  and  supe¬ 
rior  to  those  of  the  other  class.  It  is  only,  however,  when  there 
is  a  regular  and  uniform  consumption  of  collodion  that  this  form 
can  be  employed  without  waste,  or  the  risk  of  having  a  quantity 
of  material  on  hand  that  has  passed  its  best  condition. 

Collodion  which  contains  an  iodide  assumes  in  a  few  days, 
often  in  a  few  hours,  an  amber  color,  whereas  collodion  made 
with  bromides  only  (for  certain  dry  processes)  remains  as  color¬ 
less  as  water,  or  rarely  takes  a  perceptible  yellowish  shade. 

Where  it  is  desired  that  new  collodion  shall  ripen  rapidly  so 
as  to  be  fit  for  use  as  soon  as  possible,  it  should  be  kept  in  a 
warm  room  and  in  a  strong  light.  On  the  contrary,  when  it  is 
intended  to  keep  it  for  a  length  of  time,  it  should  remain  in  the 
dark,  and  in  a  cold  room,  best  in  a  cellar. 

§  4. — Effects  of  Iodine  and  Bromine. 

At  first  iodides  were  used  alone  in  connection  with  collodion. 
But  as  photographers  were  familiar  with  the  influence  of  bromine, 
bromides  were  shortly  after  used  with  collodion.  Experience  led 
(by  surprisingly  slow  degrees,  however)  to  the  recognition  of  the 
fact  that  they  were  invaluable. 

The  manner  in  which  bromides  act  is,  however,  still  a  point 
not  thoroughly  settled.  It  is  a  familiar  fact  that  iodide  of  silver 
solarizes  very  easily,  that  is,  the  maximum  effect  of  light  is  quickly 
reached,  after  which  its  action  is  reversed.  So  that  with  a  certain 
degree  of  exposure,  for  example,  the  brightest  lights  may  produce 
less  impression,  and  come  out  in  the  development  less  strongly 
than  others  of  inferior  intensity.  Bromide  of  silver  has  much 
less  of  this  tendency,  and  a  collodion  containing  bromide  has 
much  less  tendency  to  solarize. 

It  has  also  been  generally  held  that  the  use  of  iodides  was 
favorable  to  the  effects  of  force  and  contrast,  whilst  bromide 
tended  to  softness  and  the  correct  rendering  of  half  tone. 

Some  careful  experiments  made  by  the  writer  brought  him  to 
10 


138 


PHOTOGRAPHIC  MANIPULATIONS. 


the  conclusion  that  this  view  requires  a  certain  limitation,  for 
that  when  bromides  were  added  to  collodion  in  large  excess,  that 
collodion  used  in  the  wet  process,  gave  harsh  pictures,  so  that 
softness  of  effect  and  correct  rendering  of  half  tone  depend  upon 
the  judicious  combination  of  the  two.  For  example,  two  grains 
of  bromide  and  four  of  iodide  gave  a  soft  and  well-modelled 
picture.  More  bromide  Was  found  to  make  the  picture  too  soft 
and  deficient  in  contrast,  up  to  a  certain  point.  Then  the  con¬ 
trary  effect  set  in,  and  when  four  grains  of  bromide  were  used  to 
two  of  iodide,  the  picture  was  harsh. 

Another  important  function  of  bromide  of  silver  is  that  of 
keeping  the  plate  clean.  It  is  certain  that  a  bath  which  will  no 
longer  work  with  a  pure  iodide  collodion,  will  give  good  pictures 
with  one  containing  bromide.  So  with  careless  manipulation  and 
impure  chemicals,  clean  pictures  may  be  got  with  a  collodion 
containing  bromide,  when  this  would  be  impossible  with  a  simple 
iodide  collodion. 

In  the  older  formulae  employed  for  collodions,  a  great  variety 
of  substances  were  employed,  and  in  some  not  only  iodides  and 
bromides,  but  also  chlorides  and  fluorides.  Then  came  a  tendency 
to  reject  everything  but  iodides.  Next  this  was  modified  by  in¬ 
troducing  bromides,  and  it  is  by  no  means  impossible  that  we  may 
yet  find  it  advantageous  to  introduce  a  portion  of  chloride  into 
our  collodions. 

The  writer  expresses  this  opinion,  not  with  any  positiveness, 
but  as  an  idea  which  we  may  yet  see  realized.  He  has  made 
many  experiments  on  the  development  of  positive  prints  on 
paper,  and  has  been  much  struck  with  the  superiority  of  chloride 
for  this  purpose.  He  believes  that,  at  least  when  he  first  pub¬ 
lished  this  view,  it  was  contrary  to  the  prevailing  opinions, 
according  to  which  mixtures  of  iodides  and  bromides  were  pre¬ 
ferred.  But  he  found  chloride  of  silver,  though  less  sensitive 
and  needing  a  rather  longer  exposure,  to  work  far  more  evenly 
and  regularly  than  the  others,  and  he  has  little  doubt  that  a  grain, 
or  perhaps  half  a  grain  to  the  ounce  of  chloride  of  copper,  would 
be  found  an  improvement.  A  collodion  containing  three  grains 
of  chloride  of  copper,  ten  of  bromide  of  ammonium,  and  twenty- 
five  of  iodide  of  cadmium,  to  two  and  a  half  ounces  each  of 
alcohol  and  ether,  and  twenty-five  grains  of  pyroxyline,  would 
constitute  a  collodion  which  would  probably  be  found  to  have 
superior  qualities. 


PYROXYLINE  AND  COLLODION. 


139 


(Since  the  foregoing  was  written,  the  writer  has  shown  that  a 
perfectly  invisible  image  upon  chloride  paper  can  be  perfectly 
developed  with  as  full  detail  as  one  upon  bromo-iodized  paper. 
And  that  the  use  of  chloride  of  silver  in  connection  with  bromide 
in  a  particular  form  of  dry  process  (chloro-bromide  process) 
gives  most  excellent  results.) 

Experiments  made  by  the  writer  with  collodion  containing  a 
chloride  and  a  bromide  in  equivalent  proportions,  resulted  in 
showing  that  such  a  collodion  gave  faint  images  and  foggy  plates, 
with  a  bath  working  well  with  ordinary  collodions.  He  con¬ 
cluded,  therefore,  that  an  iodide  is  an  essential  constituent  of  col¬ 
lodion  for  the  wet  process,  at  least  with  baths  as  used  at  present. 
Herein  is  a  remarkable  distinction  between  wet  and  dry  processes. 
On  the  other  hand,  neither  chlorides  nor  bromides  are  essential 
to  the  wet  process,  but  good  plates  may  be  obtained  with  iodide 
of  silver  alone,  or  in  connection  with  either  bromide  or  chloride 
of  silver. 

By  some  it  has  been  argued,  that  the  beneficial  effects  of  the 
addition  of  bromide  of  silver  are  due  to  the  fact  that,  as  has  been 
stated,  bromide  of  silver  is  sensitive  to  less  refrangible  rays  than 
iodide.  That  whilst  iodide  of  silver  was  affected  by  only  the 
violet  and  bluish-violet  rays,  the  bromide  was  sensitive  to  the 
blue,  and  even,  to  some  extent,  to  the  green. 

The  writer  pointed  out,  as  far  back  as  1865,  that  the  action  of 
the  green  color  of  leaves  upon  the  collodion  film  was  very 
trifling  and  of  little  importance,  and  that  leaves  impressed  them¬ 
selves  upon  the  film,  not  by  the  agency  of  their  green,  but  of 
their  white  light. 

In  bodies  generally  we  distinguish  two  sorts  of  light  as  ema¬ 
nating  from  them.  One  reflected  from  the  surface,  which  is  white, 
whatever  be  the  color  of  the  body,  and  the  other  emanating  from 
the  interior  of  the  body,  which  is  characterized  by  color.  In 
some  cases  one  of  these  may  predominate  almost  to  the  exclusion 
of  the  other.  Perfectly  black  objects  send  us  only  surface  light, 
and  in  perfectly  white  objects  the  interior  color  is  white  as  well 
as  the  surface  color. 

Now  this  surface  light,  which  we  scarcely  take  into  account  at 
all  in  our  ordinary  observation  of  bodies  around  it,  so  completely 
is  it  masked  by  the  colored  light,  is,  in  fact,  as  the  writer  h^s  else¬ 
where  pointed  out,1  all  that  is  really  effective  to  the  photographer, 

1  Philadelphia  Photographer ,  July,  1867. 


140 


PHOTOGRAPHIC  MANIPULATIONS. 


with  the  exception  only  of  blue  or  violet-colored  bodies.  All 
bodies  of  blue-green,  green,  yellow,  orange,  and  red  colors  im¬ 
press  themselves  on  the  collodion  film  solely  by  virtue  of  the 
white  surface  light  that  accompanies,  unperceived  to  us,  the 
colored  emanations  which  they  give  forth. 

It  follows  from  this  that  there  is  little  use  in  endeavoring  to 
find  collodion  that  has  a  little  greater  range  of  impressibility. 
What  we  want  is  a  film  sensitive  to  the  very  faintest  rays  of 
white  light,  so  that  every  faintest  emanation  of  surface  light  shall 
act  upon  it  by  virtue  of  the  violet  rays  which  it  includes.  This 
high  sensitiveness  is  rarely  accompanied  with  a  great  intensity, 
so  that  it  is  precisely  the  most  sensitive  collodions  that  are  most 
apt  to  need  a  redevelopment. 

Vogel  has  published  some  interesting  experiments,  from  which 
he  concludes  that  iodide  of  silver  is  more  sensitive  to  strong 
lights,  is  more  quickly  impressed  by  them  than  bromide,  but,  on 
the  other  hand,  that  bromide  is  more  sensitive  to  weak  rays. 
Schrank  and  others  have  since  called  this  view  in  question. 
Schrank  gives  as  the  result  of  special  experiments  made  by  him, 
that  the  beneficial  influence  of  bromide  depends  upon  its  ab¬ 
sence  of  tendency  to  solarization. 

In  view  of  this  diversity  of  opinion,  and  still  more,  of  the  in¬ 
fluence  of  the  pyroxyline  itself,  it  is  not  surprising  that  the  rela¬ 
tive  quantity  of  bromide  to  iodide,  which  gives  the  best  result, 
is  still  unsettled.  It  has  been  positively  ascertained  that  the 
bromide  should  not  form  less  than  20  nor  more  than  50  per  cent, 
of  the  whole  salting.  It  may  be  said,  however,  that  the  propor¬ 
tion  of  bromide  recommended  has  steadily  increased  for  several 
years-  past,  and  with  its  increase  has  been  a  well-marked  gain  in 
the  artistic  effect  of  the  photographs  produced.  The  addition, 
moreover,  of  bromide  has  the  effect  of  rendering  the  process  far 
more  certain.  The  bath  will  continue  to  work  with  a  well-bro- 
mized  collodion  long  after  it  has  ceased  to  give  any  good  result 
with  a  simply  iodized  collodion.  The  tendency  to  stains,  fog, 
and  other  troubles  in  development  is  far  less  with  a  bromo-iodized 
collodion.  On  the  other  hand,  too  much  bromide  leads  to  the 
production  of  flat  and  monotonous  pictures,  unless,  indeed,  the 
proportion  of  bromide  be  very  much  exaggerated,  when  the 
result  again  becomes  too  harsh.  Too  much  bromide  also  tends 
to  give  a  granular  crystalline  precipitate  wanting  in  fineness. 


PYROXYLINE  AND  COLLODION. 


141 


It  now  remains  to  give  a  few  general  directions  as  to  the  pre¬ 
paration  and  management  of  collodion,  and  then  will  follow  some 
of  the  best  formulae  in  use. 

To  make  the  collodion,  the  cotton  should  first  be  weighed  and 
placed  in  the  bottle.  Three-fourths  of  the  alcohol  are  then  to  be 
added,  and  shaken  up  with  the  cotton.  Next  the  ether  is  added, 
and  the  whole  shaken  till  the  cotton  dissolves.  If  the  cotton  is 
exactly  right,  little  or  no  visible  residue  will  be  left — a  few  fila¬ 
ments  through  the  liquid,  which,  however,  will  not  be  clear. 

This  constitutes  plain  collodion ,  which  may  either  be  kept  as 
such,  or  at  once  be  sensitized  (which  is  the  better  plan)  by  dis¬ 
solving  the  salting  in  the  remaining  one-fourth  of  alcohol. 

In  preparing  a  collodion,  the  photographer  will  always  be 
guided  by  the  purpose  for  which  it  is  destined.  It  is  true  that 
collodions  can  be  made  which  will  answer  well  for  almost  any 
use  ;  but  not  so  thoroughly  well  as  a  collodion  especially  intended 
for  that  particular  employment. 

Thus  for  portraiture  there  is  a  general  preference  given  for 
collodions  containing  from  one  to  two  grains  of  a  bromide.  Here 
the  main  object  is  rapidity  and  delicacy.  The  light  is  under 
almost  complete  control  by  the  shifting  of  blinds  and  shutters, 
and  harsh  contrasts  can  always  be  avoided  by  that  control. 

With  landscapes  the  case  is  very  different.  We  take  the  light 
as  we  find  it,  and  must  enable  ourselves  to  control  our  chemicals. 
Collodions  suitable  for  portraiture  would  give  excellent  results 
in  landscape  work  in  dull  weather,  but  in  bright  there  might 
with  some  be  difficulty  in  getting  harmonious  effects.  These,  we 
secure  by  increasing  the  bromide,  if  the  collodion  in  question  be 
deficient  in  it.  Where  the  contrasts  constitute  the  main  diffi¬ 
culty,  as  in  taking  interiors  of  buildings,  or  copying  old  paint¬ 
ings,  the  proportion  of  bromide  may  be  increased  to  one-half. 
The  writer  proved  some  time  ago  that  if  we  go  beyond  this  point, 
in  place  of  obtaining  a  still  farther  increase  of  softness,  a  contrary 
effect  sets  in,  and  we  get  increase  of  contrast. 

A  difference  will  also  be  made  in  the  formula,  according  as  the 
collodion  is  needed  for  immediate  use,  or  can  be  put  aside  for 
some  time  to  ripen. 


142 


PHOTOGRAPHIC  MANIPULATIONS. 


Formula  1.  Portrait  Collodion. 


For  immediate  use. 

Alcohol  and  ether,  equal  parts 
Iodide  of  ammonium 
Bromide  of  cadmium 
Pyroxyline  .... 


.  1  ounce.1 

.  5  grains. 

.  to  2  “ 


.  6  “ 


This  collodion  can  be  used  as  soon  as  it  assumes  a  straw-color, 
or  immediately,  if  a  little  tincture  of  iodine  be  added. 


Formula  2.  Portrait  Collodion. 


To  be  kept  for  several  months  before  using. 
Alcohol  and  ether  in  equal  parts 
Bromide  of  ammonium  . 

Iodide  of  cadmium 

Pyroxyline . 


.  1  ounce. 

14  to  2  grains. 
.  5  “ 

.  6  “ 


Formula  3.  Portrait  Collodion. 

To  be  kept  six  months  in  a  cellar  before  using. 

Alcohol  and  ether,  equal  parts . 1  ounce. 

Bromide  of  cadmium  . . 11  to  2  grains. 

Iodide  of  cadmium . 5  “ 

Pyroxyline . 6  “ 

The  tendency  to  the  use  of  the  more  rapidly  ripening  collodions 
made  chiefly  with  ammonium  (Formulas  1,  4,  5,  6)  rather  than  the 
slower  ones  in  which  cadmium  preponderates  (Formulas  2,  3,  8), 
seems  to  be  on  the  increase,  though,  many  good  workers  still  prefer 
the  more  stable  sorts.  Collodions,  like  No.  3,  if  kept  in  a  cool 
place,  are  good  in  six  months,  better  at  a  year,  and  still  good  at 
eighteen  months. 

In  addition  to  the  foregoing  the  writer  gives  the  collodions  of 
some  of  the  most  successful  portraitists  in  various  countries. 


Formula  4.2  Reutlinger  (Paris). 


Ether  . 

Alcohol 
Cotton  . 

Iodide  ammonium 
“  cadmium  . 
Bromide  of  ammonium 


6  ounces. 
.  4  “ 

50  to  60  grains. 
.  30  “ 

.  20  “ 

.  5  “ 


1  It  is  important  to  understand  that  in  these  and  all  other  photographic  for¬ 
mulae  the  ounce  means  a  fluidounce  as  measured  in  a  graduate,  and  never  a 
weighed  ounce.  The  expression  is  evidently  an  incorrect  one,  but  its  use  is 
universal.  See  also  foot-note  to  p.  126. 

2  This  formula  calls  for  the  addition  of  “a  little  pure  sodium.” 


PYROXYLINS  AND  COLLODION. 


143 


Formula  5.  Sarony. 

Ether  and  alcohol,  equal  parts. 

Iodide  of  ammonium,  to  ounce  . 

Bromide  of  potassium  “  ... 

Pyroxyline . 


.  41  grains. 

.  2**  “ 

5  to  7  “ 


The  pyroxyline  to  be  treated  with  ammonia.  (See  Sec.  2  of 
this  chapter.) 

Formula  6.  Gurney. 

Ether  and  alcohol,  equal  parts. 

Iodide  of  ammonium,  to  ounce . 5  grains. 

Bromide  of  cadmium  “ . 1^  “ 

Bromide  of  ammonium . 1£  “ 

Pyroxyline . 5  to  7  “ 


3s.  1,  4,  5,  and  6  work  best  when  from  ten  to  thirty  day; 

Formula  7. 

Landscape  Collodion. 

Alcohol  .... 

. 15  ounces. 

Ether  .... 

. 15  “ 

Bromide  cadmium 

. 35  grains. 

Iodide  “  .  . 

. 80  “ 

Bromide  ammonium  . 

. 30  “ 

Iodide  “  .  . 

. 60  “ 

Pyroxyline 

. 180  “ 

This  ripens  more  rapidly  than  the  following,  in  consequence  of 
containing  iodide  of  ammonium. 

If  softer  effects  are  desired,  the  bromide  may  be  moderately 
increased,  but  too  much  of  it  will  result  in  flat  pictures  and  a 
coarsely  grained  deposit. 

Formula  8.  Landscape  Collodion. 

To  be  kept  some  weeks,  or  else  mixed  with  other  ripe  collodion. 

Alcohol  and  ether,  equal  parts. 

Bromide  of  ammonium . 2  grains. 

Iodide  of  cadmium . 41  “ 

The  sensitizing  is  done  by  placing  the  weighed  salts  in  a  test- 
tube  for  small  quantities,  or  a  flask  for  larger,  and  pouring  over 
them  the  remaining  fourth  of  the  alcohol,  not  at  once,  but  in 
successive  portions,  allowing  each  to  take  up  what  it  will  before 
pouring  it  off.  It  is  generally  expedient  to  employ  the  heat  of  a 


144  PHOTOGRAPHIC  MANIPULATION’S. 

Bunsen  burner  or  spirit  lamp  to  get  the  bromide  into  solution. 
It  is  not  worth  while  to  filter  the  solution — the  simplest  plan  is 
to  pour  it  into  the  plain  collodion,  shake  well,  and  filter  or  de¬ 
cant  afterwards. 

Bromide  of  cadmium  dissolves  very  easily  in  alcohol;  bromide 
of  potassium  and  of  ammonium,  with  much  difficulty.  But  these 
alkaline  bromides  dissolve  much  more  easily  in  a  solution  con¬ 
taining  already  bromide  of  cadmium  (because  double  salts  are 
formed,  whose  solubility  is  greater  than  that  of  the  alkaline  salt). 
Therefore  it  will  always  be  found  easiest  to  place  all  the  salts 
together  in  the  test-tube  or  flask  and  dissolve  them  together. 

Great  care  must  be  taken  of  fire,  in  all  operations  with 
ether  which  may  readily  ignite  from  a  flame  at  a  considerable 
distance.  Ether  evaporates  very  easily,  and  its  vapor  rapidly 
spreads  through  the  atmosphere — this  vapor  may  easily  become 
dense  enough  to  carry  the  flame.  For  this  reason  the  utmost  care 
is  needful,  and  accidents  with  the  heedless  are  very  common. 
The  danger  is  all  the  greater  that  as  ether  has  little  affinity  for 
water,  water  does  not  easily  extinguish  it,  the  ether  floats  on  the 
surface  and  continues  to  burn.  Wet  sand  is  the  best  application. 
If  a  quantity  of  ether  is  spilled  by  the  breaking  of  a  large  vessel, 
the  first  care  should  be  to  extinguish  every  light  and  fire  in  the 
building.  The  next  to  provide  buckets  of  wet  sand,  in  case  of 
kindling.  If  happily  this  is  avoided,  no  fire  or  match  should  be 
lighted  until  the  whole  house  has  been  so  thoroughly  ventilated 
that  the  smell  of  ether  has  disappeared. 

Many  operators  regularly  add  a  little  solution  of  iodine  to  all 
their  collodion,  and  there  is  no  doubt  that  that  system  is  the 
one  that  obviates  the  most  completely  all  danger  of  fogging. 
Others  .prefer  to  depend  upon  the  aging  or  ripening  of  the 
collodion. 

Those  who  adopt  the  former  plan  of  adding  iodine  to  the  col¬ 
lodion,  should  be  extremely  careful  about  acidifying  the  nitric  bath  • 
Perfectly  neutral  nitrate  of  silver  should  alone  be  employed,  and 
before  adding  any  acid  to  the  bath,  a  plate  should  be  tried  with 
the  collodion  intended  to  be  used,  and  if  it  works  cleanly,  then 
no  acid  must  be  introduced  into  the  bath,  or  the  sensitiveness  of 
the  film  will  be  materially  diminished.  This  point  will  also  be 
adverted  to  in  the  remarks  on  fogging. 

A  collodion  that  gives  a  thin  image  will  often  be  cured  of  this 


PYROXYLINE  AND  COLLODION. 


145 


defect  by  adding  to  it  pyroxyline  in  the  proportion  of  a  grain  or 
two  to  the  ounce.  On  the  other  hand,  coarseness  indicates  the 
presence  of  too  much  pyroxyline. 


§  5. — Clearing  Collodion. 

When  time  can  be  given,  the  simplest  and  much  the  best 
method  of  clearing  collodion  is  by  subsidence  and  decantation. 
The  collodion  is  set  aside  for  any  time  not 
less  than  a  month,  and  the  clear  part 
poured  off.  It  will  be  found,  however, 
that  the  operation  of  pouring  quickly  stirs 
up  the  sediment  at  the  bottom,  consequently 
the  method  of  transferring  represented  in 
Fig.  90  should  invariably  be  employed. 

Two  holes  are  pierced  through  a  cork,  one 
carries  a  short  bent  tube  A,  and  through 
the  other  is  passed  the  shorter  leg  of  the 
siphon  S.  By  blowing  gently  into  the 
tube  A,  the  siphon  is  started,  and  then 
continues  to  empty  the  bottle  to  the  level 
of  the  bottom  of  the  shorter  leg.  This 
last  should  be  pushed  down  to  within  a 
quarter  of  an  inch  of  the  layer  of  sediment. 

At  B  is  represented  the  size  and  weight 
of  glass  tube  which  will  be  proper.  The  siphon  is  easily  made 
by  bending  the  glass  tube  over  a  bat-wing  gas-burner  :  heavy  tube, 
though  slower  in  heating,  is  much  more  manageable  than  light. 
The  cork  should  be  very  conical,  in  order  that  it  may  fit  any  size 
of  neck  for  which  it  may  be  wanted. 

If  filtering  be  resorted  to,  then  instead  of  the  filtering  appa¬ 
ratus  commonly  employed,  in  which  the  collodion  is  filtered 
through  sponge,  the  writer  has  found  it  far  preferable  to  select  a 
piece  of  fine  strong  close-woven  linen.  This  is  thrown  into 
boiling  water  and  left  to  soak  for  some  hours  to  get  rid  of  the 
dressing;  it  is  then  well  shaken  in  cold  water  and  dried.  A 
round  piece  about  four  inches  in  diameter  is  cut.  As  the  collo¬ 
dion  runs  through  in  a  rapid  stream,  this  will  be  large  enough. 

By  preparing  a  yard  or  two  of  linen  in  this  way,  the  pho¬ 
tographer  will  be  supplied  for  an  indefinite  time ;  for  one  piece 


146 


PHOTO  OR  A  PHIC  MANIPULATIONS. 


Fig-  91  •  answers  over  and  over  again.  Although  it 

may  appear  to  have  its  meshes  completely 
stopped  by  the  solidified  collodion,  still  it  filters 
as  well  as  ever. 

Sponge  is  also  excellent  for  filtering  collodion. 
The  writer  takes  “  surgeons’  sponge,”  or  even 
a  fine  quality  of  carriage  sponge,  and  soaks  it 
for  two  or  three  days  in  hydrochloric  acid  di¬ 
luted  with  eight  times  its  bulk  of  water,  using 
plenty  of  the  dilute  acid.  This  removes  the 
calcareous  matter,  and  renders  the  whole  tex¬ 
ture  of  the  sponge  weak  and  soft.  It  is  then 
thoroughly  washed  out  with  water,  dried,  and  is 
fit  for  use. 

Whichever  is  used,  the  funnel  should  be 
covered  with  a  plate  of  glass,  as  shown  in  Fig.  91.  With  this 
precaution  the  evaporation  becomes  inconsiderable. 


\  6. — Keeping  Collodion. 

The  ripening  of  collodion  depends  upon  temperature ,  and,  pro¬ 
bably,  to  some  extent  upon  light.  If,  therefore,  it  is  desired  to 
ripen  collodion  rapidly,  it  should  be  kept  in  a  warm  light  room. 
On  the  other  hand,  if  a  quantity  is  prepared  to  be  used  over  a 
long  period,  it  should  be  placed  in  a  cool  dark  cellar.  Collodion 
chiefly  salted  with  cadmium  salts  keeps  well  and  improves  for  a 
long  time. 

It  is  well  to  understand  that  with  time  all  collodions  tend  to 
produce  a  substance  having  a  peculiarly  irritating  odor,  which 
sometimes  causes  personal  suffering  to  those  that  use  it.  Espe- 
cially  it  attacks  the  eyes,  and  cases  have  been  known  of  persons 
obliged  to  give  up  photography  for  six  months  or  a  year,  so  ob¬ 
stinate  is  the  soreness  produced  in  this  way. 


CHAPTER  IV. 


THE  NEGATIVE. 

§  1. — The  Camera. 

The  photographic  camera  should  be  made  of  mahogany  or 
cherry,  not  of  walnut,  should  be  neatly  fitted,  and  strongly  put 
together.  Small  cameras  are  often  fitted  up  with  a  removable 
partition,  so  that  they  can  be  used  either  with  two  lenses  for 
stereos,  or  with  a  single  lens.  The  front  of  the  camera  should 
permit  of  a  movement  up  and  down,  and  sideways,  in  either  case 
to  be  arrested  and  the  front  held  firm,  by  a  mill-head  screw.  This 
is  known  as  a  Sliding  Front.  The  focus  is  regulated  in  two 
different  ways,  the  camera  front  is  racked  in  and  out  by  a  long 
screw  moved  by  a  mill-head  at  the  back,  or  the  back  is  moved  in 
and  out  by  a  mill-head  that  turns  a  pinion  working  in  a  rack.  In 
the  latter  construction  a  “  pinching  screw”  serves  to  secure  the 
position  firmly  when  the  focus  has  been  taken.  Every  camera 
should  have  a  “  universal  level”  set  in,  to  enable  the  operator 
with  certainty  to  level  his  instrument.  The  universal  level  is 
about  an  inch  and  a  quarter  in  diameter,  and  contains  a  piece  of 
glass  ground  to  a  slight  curvature  somewhat  like  a  watch-glass. 
A  single  bubble  of  air  in  the  spirit  underneath,  indicates  a  true 
level  by  resting  in  the  centre  of  the  glass.  This  level  is  in¬ 
serted  in  the  camera  at  the  back,  just  behind  the  ground  glass. 
Those  who  have  cameras  unprovided  with  them,  can  procure 
them  at  a  small  cost  from  makers  of  surveying  instruments  (the 
writer’s  were  made  by  Mr.  Zentmayer,  Fourth  St.  and  Harmony 
Court,  Philadelphia).  To  insert  them  a  board  must  first  be  fixed 
in  a  perfectly  level  position.  A  hole  J  inch  deep  must  previously 
have  been  made  in  the  camera  for  the  level.  The  camera  is  set 
upon  the  accurately  levelled  board,  the  level  is  then  so  set  into 
its  cavity  that  the  bubble  will  be  in  the  centre.  A  little  cap 
cement  or  bottle  wax  serves  to  secure  it  permanently. 

The  landscape  camera  should  be  lightly  but  strongly  made  of 
the  best  seasoned  mahogany,  walnut  being  too  apt  to  crack,  and 


148 


THE  NEGATIVE. 


should  combine  lightness  for  carrying,  with  solidity.  Brass 
bindings  will  be  useful,  by  permitting  the  wood  to  be  lighter. 

Although  most  views  require  that  the  greatest  dimension  of 
the  plate  should  be  horizontal,  still  there  are  very  many  cases 
where  this  condition  can  be  advantageously  reversed,  and,  there¬ 
fore,  it  is  essential  that  the  camera  shall  be  arranged  to  screw  on 
to  the  tripod  in  either  position.  There  is  only  one  way  in  which  this 
can  he  properly  done ,  that  is,  by  having  a  wood  or  metal  cross¬ 
piece,  as  represented  in  the  figure.  That  shown  in  Fig.  92  is 
of  wood.  When  brass  is  used,  it  may  be  much  narrower,  but 
needs  a  third  arm  extending  from  the  screw-hole  A  to  the  front 
part  of  the  base  at  C.  (See  Fig.  94.) 

Sheet  brass  is  wholly  unsuitable.  A  careful  brass  casting  is 
needed,  which  must  be  stout  and  stiff. 


Fig.  92. 


If  wood  be  employed,  nothing  will  be  suitable  except  the  best 
mahogany.  The  screw-plate  must  be  set  on  the  inside ,  if  set  on 
the  outside  it  will  soon  be  pulled  off. 

After  having  given  both  a  fair  trial,  the  writer  prefers  the 
wood,  especially  for  large  cameras. 

In  cameras  made  for  sale,  there  will  often  be  found,  instead  of 
a  cross-piece  a  simple  screw-hole  at  B.  It  is  evident  that  the 
strain  resulting  from  actual  use  will  be  so  great  as  either  to  soon 
pull  the  camera  to  pieces,  or  force  it  out  of  shape.  On  the  con¬ 
trary,  the  arrangement  here  described  adds  materially  to  the 
solidity  of  the  instrument. 

The  Swing -hack  and  Swinging  Lens. — The  swing-back  is  the  most 
capita]  improvement  to  the  camera  that  has  ever  been  made.  Its 
object  and  mode  of  use  should  be  fully  understood,  and  when 
once  mastered,  this  contrivance  will  be  accepted  at  once  as  an 
indispensable  adjunct  to  both  landscape  work  and  portraiture. 


THE  CAMERA. 


149 


The  swing-back  has  two  objects  perfectly  distinct  from  each 
other.  The  first  is — 

To  render  it  possible  to  tilt  the  camera  and  yet  avoid  distortion  of 
vertical  lines. — In  making  a  view  of  any  building,  we  are  apt  to 
find  that  we  get  too  much  foreground,  whilst  the  upper  part  of 
the  building  is  apt  to  be  beyond  the  edge  of  the  plate.  To  some 
extent  we  can  remedy  this  by  pushing  upwards  the  sliding  front 
of  the  camera.  But  this  is  insufficient,  and  is  open  to  the  serious 
objection  that  as  the  axis  of  the  lens  no  longer  coincides  with 
the  centre  of  our  picture,  we  no  longer  get  the  best  definition  of 
the  lens.  So  that  only  a  little  adjustment  is  allowable  in  this 
way.  And  if  we  tilt  the  camera  upwards  all  the  vertical  lines  of 
the  building  are  intolerably  distorted. 

The  remedy  is  as  follows :  Let  E  F  represent  a  vertical  line  in 
any  building.  If  we  tilt  the  camera 
so  as  to  get  the  whole  of  it  upon 
the  plate,  the  plate  will  occupy  the 
inclined  portion  AB,  and  the  lines 
will  be  distorted.  But  if  we  can 
shift  the  back  so  that  whilst  the 
camera  is  tilted,  the  plate  can  be 
kept  in  the  vertical  position  C 
and  remain  parallel  to  E  F,  then 
there  will  be  no  distortion,  however 
much  we  may  tilt  the  camera. 

This  result  is  obtained  by  saw¬ 
ing  through  the  back  of  the  camera  and  interposing  a  few  bellows 
folds.  At  a  point  about  half  way  between  the  top  and  bottom 


Fig.  93. 


150 


THE  NEGATIVE. 


there  is  a  pivot  on  each  side,  on  which  the  back  swings,  and  on  the 
top  there  is  a  brass  slot  and  a  mill-head  which  secures  the  swing- 
back  firmly  into  any  position  that  has  been  given  it. 

This  arrangement  is,  however,  incomplete  without  a  second 
piece  exactly  similar,  but  with  its  pivots  at  top  and  bottom,  and 
slot  and  mill-head  at  sides.  As  the  first  described  permits  the 
plate  to  be  adjusted  vertically ,  it  will  be  called  for  distinction  the 
vertical  swing-bach.  And  as  the  second,  that  with  its  pivots  at 
top  and  bottom,  moves  horizontally,  it  will  be  called  the  horizon¬ 
tal  swing-back.  The  two  together  constitute  the  “  double  swing- 
back,”  and  is  represented  in  Fig.  94. 

The  second  and  perhaps  the  most  important  function  of  the 
swing-back  istoazc^  in  getting  different  parts  of  a  subject  simultaneously 
into  focus.  It  is  evident  that  with  a  double  swing-back,  the 
different  portions  of  the  plate  may  be  made  to  assume  a  great 
variety  of  positions.  Either  the  top,  the  bottom,  or  either  side 
may  be  brought  nearer  to  the  lens,  or  farther  from  it  than  the 
centre. 

Use  of  Swing-bach  in  Portraiture. — Often  the  camera  needs  to 
be  depressed  in  front  to  make  it  conveniently  include  the  whole 
of  a  standing  figure.  Here  the  first-mentioned  application  of 
the  swing-back  comes  in,  and  vertical  lines,  as  columns,  windows, 
&c.,  are  preserved  from  distortion.  The  second  application  of 
the  swing-back  finds  its  use  with  sitting  figures,  in  which  the 
feet  are  always  too  near  for  the  rest  of  the  body,  and  with  lenses 
of  long  focus  it  will  not  be  easy  to  get  them  into  focus  with  the 
face.  Being  nearer  to  the  lens,  they  will  have  a  longer  focus. 
We  have,  therefore,  only  to  move  the  vertical  swing  on*its  pivot 
so  as  to  draw  the  top  of  the  plate  back  a  little,  and  the  difficulty 
disappears.  For  this  purpose  the  pivot  A  should  be  below  the 
middle,  in  order  to  be  opposite  to  the  head,  it  being  an  object  in 
adjusting  the  swing-back  not  to  disturb  the  focus  on  the  principal 
object,  but  this  point  is  apt  to  be  overlooked  by  the  makers. 
(For  landscapes,  the  pivot  is  best  exactly  in  the  middle.) 

The  horizontal  swing-back  will  be  useful  in  taking  groups,  and 
permit  of  varying  the  grouping  in  a  way  otherwise  impossible 
with  a  portrait  lens.  With  its  aid,  the  members  of  the  group  at 
one  side  may  be  nearer  or  more  distant  than  those  at  the  other  : 
may  be  more  distant  than  the  central  ones,  and  yet  may  be  got 
into  focus  by  bringing  the  end  of  the  plate  upon  which  they  fall 
nearer  to  the  lens. 


THE  CAMERA. 


151 


Landscape  Work. — For  landscape  work  the  swing-back  is  very 
valuable  in  several  ways.  In  almost  all  views  the  foreground  is 
the  nearest  portion  to  the  camera.  Its  conjugate  focus  is  longer, 
consequently  if  the  focus  is  taken  so  as  to  embrace  satisfactorily 
the  rest  of  the  picture,  the  foreground  is  apt  to  be  wrong. 
And  if  the  focussing  slide  be  racked  back  to  bring  the  foreground 
into  correct  focus,  the  rest  of  the  picture  suffers  materially.  The 
evil  here  spoken  of  is  often  considerably  alleviated  by  curvature 
of  the  field,  but  yet  not  often  sufficiently,  and  in  lenses  possessing 
a  flat  or  nearly  flat  field,  even  this  assistance  is  wanting.  It  is 
therefore  an  immense  aid  to  be  able  to  move  the  top  of  the  plate 
a  little  away  from  the  lens. 

There  is  yet  another  use  for  this  valuable  contrivance.  It  will 
occasionally  happen  in  landscapes  that  one  side  of  the  view  is  mate¬ 
rially  nearer  to  the  camera  than  the  other.  Here  the  horizontal 
swing-back  comes  into  play.  The  side  on  which  the  nearer 
objects  fall  is  pulled  a  little  out  from  the  lens,  and  that  part 
of  the  picture  comes  into  focus  without  material  injury  to  the 
centre. 

The  combination  of  these  two  movements,  vertical  and  hori¬ 
zontal,  will  sometimes  be  valuable,  and  it  is  moreover  to  be  ob¬ 
served  that  as  the  camera  is  used  sometimes  on  its  base  and 
sometimes  on  its  side,  the  functions  of  the  two  swing-backs 
change  with  this  change.  When  the  camera  is  turned  upon  its 
side,  that  which  was  before  the  horizontal  swing-back  now  serves 
to  regulate  the  foreground.  So  that  whatever  value  is  placed  on 
the  two  modes  of  adjustment,  neither  can  be  dispensed  with,  ex¬ 
changing  functions  as  they  do.  It  is,  therefore,  a  serious  mistake 
to  purchase  a  camera  with  a  single  swing-back,  except,  perhaps, 
in  the  case  of  a  camera  to  be  used  solely  and  exclusively  for 
stereoscopic  work.  In  this  case  a  vertical  swing-back  (with 
pivots  at  the  sides)  is  principally  needed. 

Swinging  Lens. — A  little  consideration  will  show  that  results 
analogous  to  the  above  may  be  obtained  by  simply  so  setting 
the  lens  that  it  may  turn  freely  in  all  directions.  The  writer 
considers,  however,  that  the  introduction  of  this  system  as  a 
substitute  for  the  swing-back,  is  a  serious  evil.  Before  explain¬ 
ing  this,  it  will  be  proper  to  exhibit  the  action  of  the  swinging 
lens. 

Suppose  that  the  tube  of  the  lens  L  be  jointed  to  the  camera 


152 


THE  NEGATIVE. 


so  that  it  can  be  turned  in  any  direction  whilst  the  body  of  the 

camera  remains  fixed.  It  is  evident 
that  the  focussing  screen  A  B,  and 
consequently  the  sensitive  plate 
remains  vertical ,  precisely  as  if  the 
lens  had  not  moved.  And  remain¬ 
ing  vertical  it  cuts  the  cone  of  rays 
from  the  lens,  parallel  to  the  verti¬ 
cal  lines  of  any  building  that  may 
stand  before  the  lens.  These  are, 
therefore,  correctly  represented  on  the  screen  A  B,  precisely  as 
if  the  lens  L  had  remained  in  the  ordinary  position. 

But  the  tilting  of  the  lens,  whilst  it  enabled  the  camera  to 
take  in  the  higher  parts  of  any  building  before  it,  at  the  same 
time  altered  the  position  of  the  axis  of  the  lens.  This  axis  when 
the  lens  is  in  its  usual  position,  passes  through  the  centre  of  the 
camera,  but  with  the  tilting  assumes  a  new  position  L  A,  and  the 
centre  of  the  image  no  longer  corresponds  with  the  centre  of  the 
focussing  screen,  but  falls  to  A. 

To  remedy  this  the  camera  front,  carrying  with  it  the  lens,  is 
raised  until  the  axis  of  the  lens  takes  the  position  B  L  (Fig.  96). 

So  that  here  we  have  accomplished 
Fig.  96.  much  the  same  result  as  by  the  swing- 

back,  viz.,  we  have  tilted  the  lens 
so  as  to  embrace  the  higher  objects 
and  yet  have  kept  the  image  per¬ 
fectly  vertical.  With  the  swing-back 
the  centrality  of  the  axis  was  not 
disturbed,  here  it  has  been  disturbed, 
but  readjusted. 

For  this  object,  the  utility  of  the 
swinging  lens  is  probably  equal  to 
that  of  the  swing-back. 

Next,  as  to  adjusting  the  focus  for  the  foreground.  It  is  to  be 
remembered  that  the  image  is  formed  at  right  angles  to  the  axis  of 
the  lens ,  consequently  when  the  lens  is  bent  downward  and  the 
axis  takes  the  position  L  A  (Fig.  97),  the  image  is  found  in  the 
plane  B  C.  But  this  image  is  not  received  on  the  focussing 
screen  at  the  position  B  C,  but  in  that  of  D  E.  A  little  reflection 
will  show  that  this  change  corresponds  with  the  moving  back  of 


THE  CAMERA. 


153 


Fig.  97. 


the  swing-back.  That  is,  that  in 
both  cases  the  image  is  received 
on  a  plane  which,  at  the  top  of 
the  camera,  is  farther  from  the  lens . 

And  thus  in  both  cases,  the  longer 
focus  of  the  foreground  will  be  ac¬ 
commodated. 

It  is  evidently  a  fault  in  the 
swinging  lens  that  thus  to  bring 
the  foreground  of  a  landscape 
into  focus  we  are  obliged  to  tilt 

the  camera  downwards,  and  so  take  in  more  foreground.  But 
this  again  can  be  cured  by  tilting  the  body  of  the  camera 
upwards.  Let  us  say  that  we  first  arrange  the  camera  in  such  a 
position  that  we  include  just  what  we  want,  and  have  the  horizon 
line  where  we  want  it.  But  the  foreground  is  not  in  focus.  We 
therefore  first  turn  down  the  lens  somewhat,  and  then  tilt  the 
camera  upwards  until  this  tilting  brings  the  lens  into  its  first 
position.  It  is  therefore  certain  that  the  swinging  lens  can,  like 
the  swing-back,  accommodate  the  focus  of  the  foreground. 

But  its  great  inferiority  lies  in  the  way  in  which  this  is  done. 
With  the  swing-back  we  arrange  the  camera  with  the  largest 
openiug  of  the  lens  until  we  get  the  picture  exactly  composed, 
and  then  changing  the  diaphragm  as  the  case  may  need ;  if  the 
foreground  is  not  in  focus,  a  slight  adjustment  of  the  top  of  the 
plate  brings  it  right. 

With  the  swinging  lens  we  have  a  double  adjustment  to  make. 
First,  the  lens  must  be  depressed.  We  cannot  tell,  however,  how 
much,  but  can  only  make  a  trial,  then  the  camera  is  to  be  tilted, 
the  horizon  line  readjusted,  and  we  examine  if  the  proper  amount 
of  change  has  been  hit  upon.  If  the  foreground  is  not  yet  in 
focus,  or  if,  in  getting  it  into  focus,  we  have  seriously  injured  the 
focus  of  any  other  part,  in  either  case  the  manipulation  must  be 
tried  over  again.  Whereas  with  the  swing-back,  we  watch  the 
changes  and  stop  it  exactly  at  the  proper  point.  And  a  similar 
objection  holds  where  these  contrivances  are  used  to  meet  the 
case  of  the  two  sides  of  the  picture  being  at  different  distances 
from  the  lens.  Here  also  the  adjustment  with  the  swing-back  is 
the  easier. 

11 


154 


PHOTOGRAPHIC  MANIPULATIONS. 


§  2. — Selecting  the  Glass. 

None  but  very  careless  operators  will  use  a  lot  of  glass  indis¬ 
criminately.  Every  piece  should  be  gone  over  and  examined 
previous  to  cleaning  it.  The  high  price  of  plate  glass  in  this 
country  almost  wholly  excludes  it  from  photographic  use.  If  it 
could  be  obtained  at  the  same  cost  as  in  England,  France,  or  Ger¬ 
many,  none  other,  or  very  little  other,  would  be  used.  As  it  is, 
photographers  for  the  most  part  content  themselves  with  a  quality 
of  glass,  usually  of  French  manufacture,  known  as  “  photo¬ 
graphic  glass.” 

The  best  quality  of  the  glass  only  should  be  purchased.  It 
comes  in  boxes  containing  fifty  square  feet.  Opening  such  a 
box,  and  sitting  with  his  face  to  a  well-lighted  window,  the  ope¬ 
rator  examines  every  piece — 

1.  As  to  sufficient  thickness.  Thin  plates  break  too  easily  in 
the  printing  process. 

2.  As  to  curvature ,  by  running  the  eye  along  the  edges  :  a 
slight  curvature  cannot  always  be  avoided ;  but  anything  over  a 
certain  degree  of  bow  is  a  sufficient  cause  for  rejection. 

3.  As  to  blebs.  In  sun  printing  these  are  apt  to  show,  and  it 
is  generally  safest  to  reject  all  plates  that  exhibit  this  defect,  as 
it  is  difficult  to  foresee  how  much  injury  may  result  from  it. 

4.  As  to  scratches.  Some  lots  of  glass  by  careless  handling  will 
be  scratched.  All  pieces  with  scratches  visible  by  transmitted 
or  reflected  light  are  to  be  rejected.  And  to  avoid  farther  danger 
every  piece  after  examination  must  have  a  sheet  of  paper  laid 
between  it  and  the  adjoining  piece.  And  this  precaution  must 
be  kept  up  in  every  subsequent  stage  of  the  operations.  Printed 
paper  should  never  be  employed  for  this  purpose,  but  some  com¬ 
mon  though  clean  sort.  If  glass  is  left  for  some  time  in  contact 
with  printed  paper,  a  complete  impression  will  be  taken  off*  upon 
it,  and  the  difficulty  of  cleaning  will  be  proportionately  increased 
by  the  greasiness  transmitted  to  the  glass. 

5.  As  to  surface.  Some  pieces  of  glass  must  be  rejected  for 
roughness  of  the  surface. 

A  close  attention  on  the  part  of  photographers  to  these  points 
would  have  the  effect  of  obliging  those  who  manufacture  photo¬ 
graphic  glass  to  work  more  carefully  and  deliver  a  better  ma¬ 
terial. 


THE  NEGATIVE. 


155 


Preparing  the  Glass. — The  cleaning  of  the  glass  has  already 
been  explained  in  the  introduction.  A  system  has  latterly  gained 
ground  a  good  deal,  of  albumenizing  the  glass,  and  thus  obviating 
the  necessity  of  being  very  particular  in  the  cleaning.  Some 
simply  take  white  of  egg  and  shake  it  up  with  twenty  times  its 
bulk  of  water,  in  a  bottle  with  sharp  fragments  of  glass,  filter 
it,  and  make  fresh  for  each  day’s  use.  Others  mix  the  white  of 
egg  with  an  equal  bulk  of  water  and  a  little  liquid  ammonia,  a 
fluidrachm  for  a  dozen  eggs.  In  this  condition  it  keeps,  and  can 
at  any  time  be  used  by  diluting  it  with  an  ounce  of  water  to 
each  drachm  of  albumen. 

Some  prefer  to  iodize  the  albumen,  obtaining  in  that  way 
rather  more  brilliant  points — 2  or  3  grains  to  the  ounce  of  dilu¬ 
ted  albumen  will  be  sufficient.  The  albumen  is  to  be  extended 
over  the  plate  with  a  glass  rod  (by  some  a  piece  of  pasteboard  is 
preferred),  the  excess  poured  off,  and  the  plate  reared  up  to  dry. 

As  the  cleaning  of  glass  cannot  be  wholly  dispensed  with,  the 
writer  does  not  see  that  any  sort  of  cleaning  involves  less  trouble 
than  the  method  with  bichromate.  And  when  that  is  done  pro¬ 
perly,  anything  further  is  altogether  superfluous.  The  writer 
has  in  some  of  his  experimental  trials  in  dry  work  used  the  same 
plates  over  and  over  until  the  marks  made  on  the  back  with  a 
diamond  pencil  indicated  that  they  had  been  used  5,  6,  or  7 
times  each.  And  never  on  these  or  any  other  occasions  has  he 
seen  indications  of  imperfect  cleaning  or  the  reappearance  of  a 
previous  image. 


§  3. — The  Negative  Bath. 

The  course  of  proceeding  recommended  in  the  introductory 
portion  of  this  manual  involved  the  use  of  a  single  bath  of  mode¬ 
rate  size.  This  is  the  best  course  for  the  beginner,  because  he 
will  inevitably  spoil  some  of  his  first  baths,  either  by  introducing 
foreign  substances  into  them,  or  by  mistaken  treatment  with  the 
view  of  improving  them.  But  when  he  has  attained  a  certain 
familiarity  with  photographic  operations,  he  will  do  best  to  adopt 
the  two-bath  system  originally  proposed,  I  believe,  by  Mr.  Wharton 
Simpson.  In  this  mode  of  operating,  one  bath  serves  to  form 
the  sensitive  film  and  receive  the  alcohol  and  ether ;  the  second 
bath  furnishes  a  nearly  pure  silver  solution,  moistening  the  film 
and  serving  for  development. 


156 


PHOTOGRAPHIC  MANIPULATION’S. 


The  writer  prefers  to  make  these  baths  of  widely  different 
strengths.  The  first  bath  is  made  strong,  40  grains  to  the  ounce, 
because  the  stronger  the  bath  the  more  completely  the  iodide  and 
bromide  remain  in  the  film.  The  second  is  made  comparatively 
weak,  20  grains  to  the  ounce.  This  furnishes  an  ample  supply 
of  silver  for  development,  and  the  danger  of  stains  is  materially 
lessened. 

Moreover,  the  writer  advises  ample  baths — one  size  larger  than 
the  largest  size  of  plate  habitually  used,  and  not  in  any  case  less 
than  60  ounces  each. 

The  advantages  of  the  system  of  working  with  two  abundant 
baths  are  so  great  that  no  one  who  has  fairly  tried  it  will  ever 
voluntarily  use  any  other.  They  consist  in  extreme  regularity 
of  working  over  a  long  period,  so  that  the  photographer  runs 
little  risk  in  being  deceived  in  his  exposures,  in  unusual  facility 
in  obtaining  plates  of  the  right  density  without  the  annoyance  of 
redevelopment,  and  in  almost  complete  immunity  from  stains, 
marbling,  pinholes,  &c.  &c.  The  system  is,  moreover,  an  econo¬ 
mical  one.  The  impurities  are  concentrated  in  the  first  bath 
for  a  long  time,  and  when  at  last  the  working  ceases  to  be  satis¬ 
factory,  it  is  put  into  the  residues  and  the  second  receives  addi¬ 
tional  20  grains  of  nitrate  of  silver  per  ounce,  and  takes  its 
place  as  the  first  bath  with  a  new  second  bath. 

The  mode  of  making  a  bath,  and  of  during  a  propensity  to 
fog  has  been  explained  in  the  introduction.  It  remains  to  be 
said  here,  that  although  the  introduction  of  iodine  into  the  bath, 
by  working  with  a  collodion  to  which  it  has  been  added,  tends 
to  acidify  the  bath,  yet  the  effect  of  the  two  treatments  upon 
the  working  is  entirely  different.  The  writer  has  known  a  case 
of  fogging,  which  could  not  be  cured  by  any  amount  of  acidifi¬ 
cation  of  the  bath,  give  way  immediately,  under  the  addition  of 
a  little  iodine  to  the  collodion.  It  appears  from  experiments  of 
Weltzien  that  iodine  liberates  hyponitric  acid  (not  nitric)  from 
nitrate  of  silver,  and  Reynolds  ingeniously  remarks  that  as 
hyponitric  acid  by  action  of  water  splits  up  into  nitrous  and 
nitric  acid,  it  is  probably  to  the  production  of  the  nitrous  acid 
that  the  curative  influence  of  the  iodine  is  due. 

Be  this  as  it  may,  it  is  certain  that  if,  after  a  very  slight  ad¬ 
dition  of  nitric  acid  to  the  bath  (1  drop  to  20  ounces  of  bath), 
there  appears  a  disposition  to  fog,  it  is  far  better  to  add  iodine  to 


THE  NEGATIVE. 


157 


the  collodion  than  to  go  on  acidifying  the  bath.  This  it  is  im¬ 
portant  for  the  photographer  to  bear  steadily  in  mind.  Also 
that  a  bath  that  fogs  badly  with  collodion  in  which  cadmium 
salts  predominate  may  not  improbably  do  well  with  a  collodion 
chiefly  salted  with  ammonium  salts. 

The  nitrate  of  silver  should  be  perfectly  neutral.  Most  per¬ 
sons  prefer  the  crystallized ;  the  writer  has  generally  used  the 
fused  in  preference.  .Crystallized  nitrate1  can  be  converted  into 
fused  by  melting  it  in  a  Berlin  porcelain  basin  over  a  Bunsen’s 
burner ;  it  should  be  kept  in  fusion  for  a  time  proportionate  to 
the  quantity — five  minutes  for  several  ounces,  and  for  quantities 
of  one  or  several  pounds,  ten  minutes.  It  is  allowed  to  cool  in 
the  basin,  and  removed  by  inverting  the  basin  upon  a  sheet  of 
letter  paper  placed  on  a  board,  the  board  is  then  tapped  on  the 
back  of  a  chair,  and  the  jarring  loosens  the  cake  without  break¬ 
ing  the  basin. 

A  negative  bath  may  by  careful  treatment  be  used  for  a  won¬ 
derfully  long  time.  The  writer  has  been  informed  by  a  profes¬ 
sional  photographer  that  he  had  made  considerably  over  2000 
negatives,  many  of  them  10  x  12  size,  in  two  4-gallon  baths,  and 
had  them  both  still  in  excellent  order.  When  they  ceased  to 
give  good  results  he  added  carbonate  of  silver,  boiled  down, 
filtered,  sunned  well,  filtered  again,  acidulated  and  strengthened. 

When  the  bath  gives  pinholes  it  must  be  poured  into  its  own 
bulk  of  water,  filtered,  and  after  filtering,  be  evaporated  down 
to  its  original  bulk. 

The  writer,  in  working  the  wet  process,  has  generally  adopted 
the  principle  of  not  wasting  time  and  patience  in  trying  to  bring 
faulty  baths  into  working  order,  but  had  made  it  a  rule  to  sub¬ 
stitute  a  new  bath,  putting  the  old  one  aside  until  a  proper  quan¬ 
tity  collected.  These  are  then  to  be  evaporated  down  in  a  large 
basin,  large  enough  to  hold  perhaps  a  fifth  at  a  time,  of  the 
whole  quantity.  As  fast  as  the  liquid  goes  down,  more  is  added. 
When  the  liquid  becomes  small  in  bulk,  it  is  transferred  to  a 
smaller  basin  of  first  quality  Berlin  or  Meissen  porcelain,  and 
heat  applied  until  all  the  water  goes  off,  and  a  powdery  mass  is 
left.  The  heat  is  then  carefully  raised  till  the  whole  mass  passes 

1  One  hundred  and  eight  parts  of  pure  silver  correspond  to  one  hundred  and 
seventy  parts  of  nitrate.  The  mint  value  of  pure  silver  is  $1  40  in  silver, 
per  troy  ounce.  Metallic  silver  is  sold  by  the  troy  ounce  (480  grains),  nitrate 
of  silver  by  the  ounce  avoirdupois  (437^  grains). 


158 


PHOTOGRAPHIC  M  A  A.IPUL  ATIONS. 


into  quiet  fusion,  in  which  condition  it  is  kept  five  or  ten  minutes, 
not  longer.  After  cooling,  the  cake  of  nitrate  is  broken  up  and 
used  for  new  baths,  acidulating  with  dilute  nitric  acid  if  necessary. 

Some,  before  evaporating,  dilute  largely  with  water  to  throw 
down  the  iodide.  This  makes  an  immense  mass  of  material  to 
evaporate,  and  in  the  writer’s  experience,  has  not  been  necessary. 
If  when  the  fused  cake  is  dissolved,  hot'  water  is  used,  and  the 
solution  filtered  at  once,  most  of  the  iodide  will  remain  undis¬ 
solved.  The  full  quantity  of  water  needed  for  the  bath  should 
be  added  to  the  cake  at  once,  and  not  a  strong  solution  first  made 
and  then  diluted. 

A  second  bath,  in  first-rate  order,  should  always  be  kept  on 
hand  to  avoid  the  need  of  hurriedly  treating  a  bath  that  has 
ceased  to  work  well.  The  plan  of  having  a  second  weaker  bath 
to  redip  the  plates  after  the  first,  already  described,  cannot  be 
too  much  recommended. 

Swinging  Bath. — In  the  ordinary  dipping  bath,  if  any  scum 
forms  on  the  surface  of  the  liquid,  it  is  apt  to  settle  on  the  plate 
as  the  latter  is  lifted  face  upward  on  the  dipper.  This  may  be 
avoided  by  swinging  the  bath  on  pivots  half  way  up.  The  plate 
is  put  in,  with  the  bath  in  its  regular  position,  the  bath  is  then 
swung  forwards  until  the  plate  tips  over  with  its  front  upper 
corners  on  the  other  side  of  the  bath.  In  this  way  when  worked 
up  and  down,  the  face  of  the  plate  is  continually  washed,  and 
when  drawn  out,  the  scum  attaches  itself  to  the  back  of  the 
plate  instead  of  the  front. 

|  4. — Making  the  Plate. 

The  mode  of  coating  the  plate  has  been  already  described  and 
illustrated  with  explanatory  figures.  (See  p.  22.)  In  the  first 
edition  of  this  manual,  the  course  habitually  taken  by  photog¬ 
raphers  in  coating  blown  glass,  viz.,  to  coat  the  hollow  side,  was 
recommended.  The  reasons  in  favor  of  this  course  are,  first  and 
principal,  the  curvature  of  the  field  exhibited  by  many  lenses, 
and  secondly,  that  when  the  hollow  side  is  coated  the  pressure  of 
the  spring  of  the  dark  slide  acts  to  some  extent  as  a  corrective, 
flattening  the  plate. 

Continued  experience  inclines  the  author  to  believe  that  this 
system  cannot  always  be  advantageously  employed,  but  that  in 
a  considerable  number  of  cases,  the  reverse  is  the  proper  plan. 


THE  NEGATIVE. 


159 


In  most  landscapes  the  most  distant  objects  occupy  a  position 
towards  the  centre  of  the  plate;  the  objects  occupying  the  sides 
are  mostly,  and  those  occupying  the  lower  edge  are  almost  in¬ 
variably,  nearer  to  the  camera  than  the  central  objects.  It,  there¬ 
fore,  follows  that  the  central  objects  will  be  apt  to  have  a  focus 
shorter,  often  considerably  shorter  than  those  occupying  the  mar¬ 
gins  of  the  plate.  This  fact  every  practical  photographer  will 
have  very  often  noticed.  And  if  this  is  so,  it  is  clear  that  what¬ 
ever  difficulty  there  may  be  in  bringing  these  parts  simulta¬ 
neously  into  focus  upon  the  ground  glass,  the  case  will  be  yet 
worse  on  the  sensitive  plate  if  coated  on  its  hollow  side,  whereas 
if  it  be  coated  on  the  convex  side,  the  centre  of  the  plate  will 
approach  nearer  to  the  lens,  and  consequently  tend  to  remedy 
the  defect. 

It  we  apply  these  principles  to  photographic  subjects  generally 
we  shall  conclude  that  when  the  different  objects  included  in  the 
pictures  are  nearly  in  the  same  plane ,  we  should  coat  the  hollow 
side.  Therefore  in  portraits,  and  in  views  of  architectural  sub¬ 
jects,  the  hollow  face  should  be  coated. 

On  the  other  hand,  when  landscapes  are  to  be  taken,  with  the 
central  objects  farthest,  it  will  be  best  to  coat  the  convex  side. 

In  some  landscapes  the  nearest  objects  are  at  one  side,  and  as 
we  pass  towards  the  other  side  of  the  plate  they  continually  in¬ 
crease  in  distance.  This  is  not  a  common  case,  and  is  to  be 
managed  by  the  use  of  the  swing-back,  drawing  back  that  part 
of  the  ground  glass  upon  which  the  nearer  objects  fall. 

To  the  remarks  already  made  in  Part  I.,  the  following  may  be 
added: — 

Pneumatic  Holders . — These  are  of  two  sorts;  the  one  intended 
for  collodionizing  with,  is  made  entirely  of  rubber.  If  the  cup 
portion  be  wetted  and  pressed  firmly  against  the  glass  at  the 
middle  of  the  back,  it  adheres  and  affords  a  convenient  handle. 
Some  have  a  hollow  chamber  below  (see  Fig.  98), 
by  squeezing  the  air  out  of  which,  the  adhesion  is  Fig.  98. 
improved.  These  holders  avoid  the  danger  of 
mottled-marks  produced  by  the  warmth  of  the 
fingers  touching  the  under  side  of  the  glass,  but 
must  be  used  with  care.  They  must  be  wetted  to 
adhere.  If  set  down  in  places  soiled  by  spilled  so¬ 
lutions,  these  may  be  transferred  to  the  back  of  the 


160 


PHOTOGRAPHIC  MANIPULATIONS. 


plate,  and  thence  to  the  negative  bath,  to  its  destruction.  And 
occasionally  the  adhesion  will  give  way  during  the  pouring  off: 
the  operator  must  be  prepared  for  this,  and  if  he  feels  the  plate 
slipping,  must  support  it  by  the  ends  of  the  fingers  till  he  can 
get  hold  of  the  corner. 

Fig.  99. 


I 


Another  sort  is  useful  for  keeping  the  hands  clean  during  de¬ 
velopment.  (Fig.  99.) 

A  good  manipulator  will  find  both  these  instruments  useful. 

As  the  film  dries,  the  surface,  which  looked  before  perfectly 
smooth,  will  frequently  show  minute  specks,  which,  by  capillary 
attraction,  cause  the  collodion  to  collect  round  them  so  that  they 
form  slightly  raised  spots.  These  are  one  of  the  great  nuisances 
of  photography,  and  one  which  no  carefulness  of  manipulation 
will  get  rid  of.  The  writer  has  even  tried  forcing  collodion 
through  thick  filtering  paper  by  the  pressure  of  a  considerable 
column,  but  the  collodion  so  filtered  produced  them  just  as  much 
as  that  filtered  through  sponge.  These  specks,  as  far  as  he  can 
find,  depend  upon — 

1.  Minute  filaments  carried  through  the  filter  (if  sponge)  or 
coming  from  the  filter  itself  (if  paper  or  cotton-wool). 

2.  Dust  on  the  plate  before  pouring. 

3.  Dust  falling  during  the  collodionizing. 

4.  Dust  on  neck  of  collodion  bottle. 

Of  course  cause  (1)  is  beyond  helping,  and  is  therefore  the 
most  serious  of  all.  To  obviate  (2)  brush  the  plate  gently  with  a 
soft  wide  camel’s  hair  brush,  or  rub  gently  and  very  moderately 
with  blotting-paper  moistened  with  alcohol,  just  before  collo¬ 
dionizing.  Not  using  too  much  friction,  or  it  will  very  easily 
become  electrical  and  attract  every  mote  in  the  atmosphere,  and 
retain  it  obstinately. 

Cause  (3)  is  best  obviated  by  having  a  special  closet  in  the 
dark  room  for  collodionizing.  This  is  so  desirable  on  hygienic 
grounds  alone,  that  it  should  never  be  omitted. 

Often  these  specks  may  be  floated  off  by  pouring  on  a  good 
quantity  of  collodion,  so  that  the  excess  in  flowing  off  the  plate 
may  carry  the  speck  or  mote  with  it. 


THE  NEGATIVE. 


161 


Only  experience  can  enable  the  photographer  to  decide  as  to 
whether  a  film  showing  some  of  these  specks  must  be  wiped  off 
again.  If  intended  for  copying,  it  must,  invariably,  be  rejected  ; 
and,  generally,  if  for  portraiture.  In  landscape  work,  one  or  two 
small  specks  are  not  likely  to  show  in  the  negative. 

This  is  on  the  supposition  that  the  particles  are  filaments  of 
wool,  or  cotton,  or  other  inert  substance.  Sometimes  there  may 
be  chemical  dust,  as  of  hyposulphite  of  sodium,  in  the  atmos¬ 
phere.  In  this  case  the  speck,  after  sensitizing,  will  appear 
darker  than  the  rest  when  viewed  by  transmitted  light,  and  the 
plate  is,  of  course,  worthless. 

Attention  to  the  proper  moment  for  dipping  into  the  bath  is 
necessary,  because,  if  the  plate  be  kept  too  long,  it  is  insensitive, 
and  tends  to  marbled  stains ;  if  plunged  in  too  soon,  it  may  split 
in'  the  bath.  But  even  if  the  film  does  not  split,  it  *may  still  not 
have  been  dry  enough,  and  may  exhibit  an  appearance  which  no 
one,  without  instruction,  would  ascribe  to  the  right  cause.  Some 
portion  of  the  film  will  assume  a  peculiar  appearance,  not  easily 
described,  but  very  observable.  Perhaps  a  better  idea  can  be 
given  by  saying  that  it  has  something  the  appearance  of  wax, 
the  structure  of  a  freshly -broken  cake  of  camphor,  or  of  fused 
nitrate  of  silver  ;  neither  exactly  conveys  the  idea,  but  are  per¬ 
haps  as  good  comparisons  as  can  be  found.  This  appearance  is 
rarely  at,  or  carried  to,  the  edges,  which  dry  faster,  but  is  gene¬ 
rally  to  the  interior  of  the  plate,  and  mostly  covers  a  few  square 
inches  of  surface.  It  rather  gives  the  idea  of  some  decomposi¬ 
tion  to  the  collodion,  than  suggests  its  true  origin. 

On  the  whole,  it  is  perhaps  better  to  remove  the  plate  from 
the  bath  as  soon  as  the  greasy  marks  disappear.  At  this  stage 
the  iodides  and  bromides  are  still  in  excess  at  the  bottom  of  the 
film  ;  this  bottom  is  therefore  insensitive,  and  consequently  the 
sensitive  portion  of  the  film  is  separated  by  this  insensitive  por¬ 
tion  from  contact  with  the  glass,  and  thus  the  danger  of  stains 
from  imperfect  clearing  is  greatly  diminished. 

It  has  seemed  to  the  writer  that  short  immersions  in  the  bath 
tend  to  produce  images  that  rest  on  the  film  and  are  whitish 
powdery.  Longer  immersion  gives  an  image  more  in  the  film, 
and  a  rich,  creasy-looking  negative.  In  this  respect  the  advan¬ 
tage  seems  on  the  side  of  a  little  longer  immersion. 


162 


PHOTOGRAPHIC  MANIPULATIONS. 


§  5. — Developers  and  Development. 

Gallic  acid,  the  first  developing  agent  used,  was  in  time  super¬ 
seded  by  pyrogallic  acid,  obtained  from  gallic  acid  by  sublima¬ 
tion.  Proto-sulphate  of  iron  was  found  to  give  a  softer  picture, 
and  needs  less  exposure  than  pyrogallic  acid,  and  has  by  degrees 
wholly  taken  its  place  in  wet  plate  development. 

Operators  differ  a  good  deal  in  their  views  as  to  the  proper 
strength  of  the  iron  developer  for  ordinary  exposures,  using  from 
ten  grains  of  sulphate  to  the  ounce  up  to  forty  or  more.  The 
following  proportion  will  be  found  to  give  good  results.  It  will 
be  needful,  however,  to  bear  always  in  mind  what  has  been  said 
on  maintaining  a  due  relation  between  the  collodion  and  the  de¬ 
velopment  (p.  132),  and  to  suit  the  developer  to  the  needs  of  the 
film.  A  collodion  containing  much  bromide  will  need  a  stronger 
developer  than  one  containing  less,  and  it  will  also  need  a  longer 
development,  because  the  deposit  is  more  crystalline,  and  not  so 
close  and  dense ;  it  lets  more  light  through,  and  will  give  a  weak 
print  unless  the  development  is  carried  farther  than  in  the  case 
of  a  collodion  containing  less  bromide. 

No.  1.  Stronger  Developer. 

Sulphate  of  iron  . 3  ounces. 

Acetic  acid . 3  to  4  ounces  fluid. 

Water . 40  ounces  fluid. 


No.  2.  Weaker  Developer. 

Sulphate  of  iron . 2  ounces. 

Acetic  acid . 3  to  4  fluidounces. 

Water . 40  ounces  fluid. 

Aids  to  Development. — In  developing  plates,  and  still  more  in 
redeveloping  them  with  pyrogallic  acid  and  silver,  the  hands  are 
apt  to  be  much  stained,  and  various  contrivances  have  been  sug- 


Fig.  100. 


gested  for  avoiding  this  annoyance.  The  author,  after  trying 
such  as  had  been  proposed,  with  no  satisfaction,  devised  one,  of 
which  the  construction  is  explained  in  the  adjoining  figure. 


THE  NEGATIVE. 


163 


Two  brass  rods,  one  considerably  longer  than  the  other,  are 
fastened  firmly  into  a  wooden  handle.  At  their  ends  the  rods 
lead  at  right  angles,  and  have  pieces  of  silver  soldered  on  to 
them.  A  rod  passes  through  these,  through  one  end  it  simply 
turns,  but  fits  into  the  other  with  a  screw  thread.  A  mill  head 
enables  one  to  turn  it  conveniently.  The  plate  is  grasped  so 
tightly  as  to  give  a  perfect  security,  without  ever  being  broken. 

An  ingenious  contrivance  for  the  same  purpose  was  communi¬ 
cated  to  the  author  by  Mr.  Henderson,  of  Montreal.  A  brass 

Fig.  101. 


rod  A  C  has  a  knob  fixed  at  its  end  A,  made  by  heating  a  piece 
of  gutta  percha  and  kneading  it  into  shape  while  hot.  A  notch 
is  made  under  it  to  receive  the  edge  of  the  plate.  A  short  piece 
of  lead  pipe,  B,  slides  on  the  rod  and  is  held  by  the  thumb 
against  the  plate,  which  it  holds  in  place.  This  plan  is  simpler 
than  the  first  described,  but  does  not  give  equal  security. 

If  any  repellant  action  show  itself  between  the  developer  and 
the  film,  alcohol  must  be  added  to  the  developer,  in  such  pro¬ 
portion  as  will  check  this  tendency.  An  ounce  of  alcohol  to 
eight,  ten,  or  twelve  of  developer  may  be  needed.  This  is  a 
matter  of  no  small  importance,  because  the  repellant  tendency 
may  at  any  moment  lead  to  the  formation  of  oily  lines,  and  these, 
unless  the  plate  is  instantly  washed  off,  almost  inevitably  produce 
streaks. 

When  sulphate  of  iron  is  used  for  developing  instantaneous 
pictures ,  no  restraining  acid  is  employed,  but  simply  a  very  strong 
solution  of  the  iron,  80  or  100  grains  to  the  ounce.  Such  a  de¬ 
veloper  cannot,  of  course,  be  kept  on  more  than  a  very  short 
time,  and  the  image  once  forced  out,  recourse  must  be  had  to 
redevelopment,  or  to  after-intensification,  to  bring  the  image  up 
to  printing  strength.  Conversely,  when  a  long  exposure  has 
been  given,  a  good  deal  of  restraining  acid  may  with  propriety 
be  added. 

It  has  been  proposed  at  various  times  to  place  a  very  great 
number  of  various  organic  substances  in  the  developer.  Expe¬ 
rience  has  shown  that  almost  any  organic  substance  may  take  the 
place  of  acetic  acid  as  a  restraining  agent,  and  sometimes  with 
advantage;  for  some  of  these  substances  have  a  remarkable 


164 


PHOTOGRAPHIC  MANIPULATION'S. 


power  of  destroying  the  tendency  to  fog,  so  that  the  iron  de¬ 
veloper  can  be  kept  upon  the  plate  like  a  pyrogallie  developer. 
Thus  redevelopment  becomes  wholly  superseded,  and  the  picture 
is  always  finished  at  a  single  operation.  The  substance  that  pos¬ 
sesses  this  property  in  the  largest  degree  is,  as  shown  by  the 
writer,  gelatine,  that  has  been  treated  with  sulphuric  acid,  with 
formation  of  glycocine  and  tyrosine.  The  writer  published  several 
formulae  for  this  purpose,  and  the  subject  attracted  at  one  time 
very  great  attention.  Many  experimenters  went  to  work  at  it, 
and  produced  formulae  of  their  own.  Since  publishing,  some 
years  ago,  the  remarks  on  the  subject  that  gave  the  initiative  to 
what  has  since  been  written,  the  writer  has  remarked  that  the 
quantity  of  sulphuric  acid  necessary  to  modify  the  gelatine  is 
absolutely  so  small  in  proportion  that  it  exercises  no  hurtful 
agency  upon  the  development,  and  consequently  it  does  not  require 
to  be  removed  by  a  subsequent  neutralization.  This  brings  the  pre¬ 
paration  of  the  collo-developer  to  a  singularly  simple  form,  as 
follows :  Take 

Common  glue . 6  ounces. 

Sulphuric  acid . f  fluidounce. 

Water . 9  fluidounces. 

f 

Boil  these  together  for  a  couple  of  hours  in  a  flask,  replacing  the 
water  as  it  evaporates.  Then  throw  in  an  ounce  of  granulated 
zinc,  and  boil  for  an  hour  and  a  half.  Add  water  as  it  evapo¬ 
rates,  and,  when  done,  dilute  to  twelve  ounces. 

This  syrupy  liquid  has  the  most  extraordinary  restraining 
power.  A  single  drop  is  sufficient  for  three  ounces  of  80-grain 
iron  solution;  one  ounce,  therefore,  of  the  above  gelatine  solu¬ 
tion  is  sufficient  for  1500  ounces  of  developer. 

Two  essential  remarks  remain  to  be  made  in  reference  to  this 
process.  It  might  be  alleged  that  the  restraining  power  is  due  to 
the  sulphuric  acid  by  reason  of  its  powerfully  acid  nature ;  but 
the  writer  has,  by  careful  experiment,  demonstrated  the  fact  that 
sulphuric  acid  does  not  tend  to  restrain  development,  but  tends 
to  fog.  It  is  therefore  clearly  not  the  sulphuric  acid  that  acts. 

Again,  it  may  be  alleged  that  by  the  long  boiling  with  zinc, 
the  whole  of  the  sulphuric  acid  must  have  been  removed  by  the 
excess  of  zinc  present.  But  the  presence  of  the  gelatine  checks 
the  action  of  the  acid  on  the  zinc  so  much  that  it  was  ascertained 
by  careful  experiment  that  when  the  operation  is  performed  as 
above  described,  at  the  end  of  a  boiling  of  an  hour  and  a  half, 


THE  NEGATIVE. 


165 


only  one-fourth  of  the  sulphuric  acid  was  neutralized.  This  was 
ascertained  by  weighing  the  zinc  before  and  after  the  operation, 
and  determining  the  quantity  of  sulphuric  acid  corresponding  to 
its  loss  of  weight. 

The  action  of  the  gelatine  in  this  case  in  checking  chemical 
action,  prevents  a  very  striking  analogy  to  its  action  in  the 
development. 

The  collo-developer,  obtained  by  adding  one  drop  of  the  gela¬ 
tine  solution,  prepared  as  above,  to  three  ounces  of  water  and  90 
grains  of  protosulphate  of  iron,  develops  rapidly  and  with  less 
tendency  to  fog  than  the  common  iron  developer.  By  somewhat 
increasing  the  quantity,  the  development  goes  on  still  more 
slowly,  with  still  less  tendency  to  fogging. 

The  Sugar  Developer. — For  the  regular  needs  of  the  photog¬ 
rapher  no  developer  can  be  better  than  the  sugar  developer. 
The  writer  uses  a  formula  of  his  own  which  he  strongly  recom¬ 
mends.  It  is  as  follows : — 

In  32  ounces  of  hot  water  dissolve  7  ounces  of  protosulphate 
of  iron.  This  is  best  done  by  letting  a  portion  of  the  hot  water 
stand  over  the  crystals  until  it  is  pretty  well  saturated,  pouring 
it  off,  and  repeating  it  with  a  second  and  third  portion.  To  this 
solution  add  6  ounces  of  white  sugar  and  2J  ounces  of  acetic 
acid  No.  8.  This  need  not  be  filtered.  It  is  the  sugar  developer 
in  a  concentrated  form,  and  keeps  indefinitely.  To  prepare  for 
use  take — 


Above  solution 
Acetic  acid  No.  8 
Water 
Filter. 


7£  ounces. 
4  “ 

18  “ 


It  is  perhaps  an  improvement  to  add  a  little  sulphate  of  cop¬ 
per.  An  ounce  of  it  may  be  added  to  the  10  ounces  of  sulphate 
of  iron.  With  it,  or  without  it,  excellent  results  are  got.  The 
strength  above  given  is  suitable  for  winter,  and  may  be  diluted 
with  from  one-half  to  an  equal  quantity  of  water  in  summer. 

Management  of  Development. — By  close  attention  to  the  manipu¬ 
lations  of  the  development  something  may  be  done  towards  con¬ 
trolling  the  nature  of  the  image  produced.  Softness  will  be  pro¬ 
moted  by  keeping  the  plates  still  whilst  the  image  is  coming 
out; — contrast  will  be  increased  by  inclining  the  plate  alternately 
at  each  end  and  keeping  the  developer  continually  in  motion, 
because  in  this  way  the  silver  solution  which  impregnates  the 


166 


PHOTOGRAPHIC  MANIPULATIONS. 


film  is  much  more  washed  out  and  mixed  up  with  the  developer. 
The  strong  parts  of  the  image  will  always  rapidly  abstract  the 
silver  from  the  solution  upon  their  portions  of  the  plate;  thus  as 
the  image  comes  out  the  shadows  will  continue  to  be  moistened 
with  a  solution  rich  in  nitrate  of  silver,  after  that  which  bathes 
the  high  lights  has  been  more  or  less  impoverished.  This  state 
of  things  is  changed  by  keeping  the  developer  in  motion ;  more 
silver  is  then  carried  to  the  high  lights,  and  contrast  is  heightened. 

With  very  large  plates  it  will  be  best  to  develop  in  a  pan. 
The  developer  is  poured  in  abundant  quantity  to  the  lower  end 
of  the  tilted  pan,  one  end  of  the  negative  is  placed  in  the  dry 
(upper)  end  of  the  pan.  The  pan  is  then  brought  to  a  horizontal 
position,  and  at  the  same  time  the  negative  is  let  gently  down 
into  it.  In  this  way  a  wave  of  developer  passes  evenly  over  the 
whole  surface.  Unless  flatness  of  effect  is  dreaded,  it  will  be 
best  to  leave  the  negative  at  rest  in  the  developer,  and  not  to 
work  backwards  and  forwards. 

It  follows  from  what  has  been  said  here  and  elsewhere  that 
the  operator  must  be  governed  in  his  development  by  a  principle 
quite  different  from  that  which  guides  him  in  exposure.  For 
whilst  his  exposure  must  be  timed  with  a  view  to  the  worst  illu¬ 
minated  part  of  the  subject,  the  development  will  be  guided  by 
the  high  lights.  These  two  principles  are  of  such  capital  im¬ 
portance  that  they  cannot  be  repeated  too  often,  or  mastered  too 
thoroughly.  They  may  be  expressed  in  two  rules,  as  follows: — 

Expose  the  plate  for  the  dark  shadows,  leaving  the  lights  to  be 
cared  for  in  the  development. 

Develop  for  the  high  lights,  keep  the  eye  steadily  fixed  on  the 
very  highest  light  (the  densest  spot)  of  the  plate,  and  stop  whilst 
that  is  transparent  enough  to  preserve  its  perfect  moulding  in  the 
print  to  be  made  from  it.  The  shadows  are  not  to  be  watched  in 
developing  (except  in  local  redevelopment ,  see  below);  they  have 
been,  or  should  have  been,  cared  for  in  the  exposure.  Not  that 
they  are  indifferent,  far  from  it,  but  in  point  of  fact,  watching 
the  high  lights  is  doing  the  best  possible  for  the  shadows,  the 
object  of  continuing  the  development  as  long  as  possible  being 
to  get  out  as  much  detail  in  the  shadows  as  possible.  Not  they, 
however,  but  the  high  lights  are  to  be  watched,  because  we  so 
ascertain  the  exact  -moment  at  which  the  development  can  be 


THE  NEGATIVE. 


167 


pushed  no  farther,  but  must  stop  under  pain  of  producing  chalki¬ 
ness  and  flat  lights,  which  are  simply  ruinous. 

Too  much  attention  cannot  be  directed  to  this  matter.  It  will 
be  necessary  for  the  photographer  to  learn  by  experience  the 
appearance  of  the  deposit  when  it  has  reached  a  point  beyond 
which  it  must  not  go.  This  cannot  be  expressed  or  described, 
can  only  be  learned  by  care  and  attention,  and  at  the  expense  of 
spoiled  plates.  It  is  of  course  to  be  judged  of  by  holding  the 
plate  up  to  the  light ;  by  degrees  the  operator  will  learn  the 
point  to  which  he  can  go  safely.  With  practice  the  photographer 
will  pick  out  at  once  the  high  light  which  he  must  watch ;  he 
will,  in  fact,  have  seen  it  in  the  subject  before  he  uncovered  his 
lens,  and  his  attention  will  be  directed  to  it  as  soon  as  he  raises 
the  plate  to  the  light.  On  this  portion  his  attention  will  be 
fixed  throughout  the  development,  and  his  anxiety  will  be  always 
that  it  shall  not  reach  the  point  at  which  it  must  stop  before  he 
gets  the  desired  detail  in  the  dark  shadows.  It  has  already  been 
remarked  that  great  care  will  always  be  needed  in  raising  the 
plate  to  observe  the  stage  reached,  lest  the  developing  solution 
break  its  even  film  into  lines,  producing  streaks  of  unequal  de¬ 
velopment,  a  trouble  that  besets  every  photographer  in  his  earlier 
work. 

Influences  controlling  the  Character  of  the  Negative. — Whatever 
influences  in  development  tend  to  softness  will,  if  exaggerated, 
tend  to  fogginess,  and  whatever  helps  brilliancy  will,  if  exagge¬ 
rated,  produce  harshness,  because  harshness  and  fogginess  are 
the  extreme  terms  of  development. 

Those,  therefore,  who  seek  for  the  softest  effects  will  endeavor 
to  keep  just  inside  the  line  of  fogging,  and  by  the  use  of  a  strong 
developer  will  equalize  the  deposit  of  silver.  Those  who  are 
anxious  for  brilliancy  will  use  a  weak  developer,  which  will  in¬ 
crease  contrasts. 

The  anxiety  for  brilliancy  which  at  one  time  existed  has  nearly 
disappeared.  The  magnificent  effects  of  half-tone  which  have 
been  attained  by  skilful  photographers  have  produced  universal 
desire  for  imitation.  In  fact,  if  different  series  of  photographs 
be  compared,  it  will  be  found  that  they  are  most  pleasing  in  pro¬ 
portion  to  the  amount  of  half-tone  that  they  contain,  and  the 
recognition  of  this  fact,  both  amongst  photographers  and  the 
general  public,  is  every  day  becoming  more  widespread. 

If  a  portrait  is  harsh,  crude,  and  unpleasing,  with  a  want  ot 


168 


PHOTOGRAPHIC  MANIPULATIONS. 


relief  in  its  various  parts ;  if  the  figure  seems  resting  against  the 
background,  and  if  the  eye  has  to  examine  the  whole  to  estimate 
the  relative  positions  of  the  parts,  the  capital  fault  (besides  what 
others  may  exist)  will  be  want  of  half-tone.  A  landscape  that 
wants  half-tone  will  be  patchy  and  blocky ;  it  will  have  a  certain 
narrow  and  scant  effect,  an  absence  of  boldness  and  breadth ;  the 
eye  will  not  at  a  glance  take  in  the  relative  position  and  bearing 
of  its  parts,  but  requires  some  moments  of  observation  before  it 
recognizes  where  everything  belongs,  and  perceives  that  certain 
parts  belong  to  the  middle  distance,  so  that  the  picture  is  not  all 
foreground  and  distance,  as  it  at  first  appeared  to  be.  In  such 
work,  the  leaves  in  the  foreground  will  be  either  white,  if  well 
illuminated,  or  black,  if  not.  It  is  such  work  that  has  led  to  the 
epithet  of  unartistic,  so  freely  bestowed  by  artists  upon  the  pro¬ 
ductions  of  photography. 

How  then  is  this  invaluable  half-tone  to  be  attained  ?  The 
answer  is  not  so  easy.  First,  it  may  be  premised  that  it  is  the 
use  of  bromides  in  collodion  that  has  made  it  possible,  the  use, 
not  the  exaggeration.  Experience  has  shown  that  broad  and  ex¬ 
pressive  half-tones  do  not  depend  upon,  and  cannot  be  reached  by 
any  particular  composition  of  collodion  or  of  developer  alone, 
but  will  depend  upon  a  happy  combination.  And  that  in  every 
case  the  conditions  necessary  can  only  be  discovered  by  careful 
and  intelligent  observation.  For  any  good  specimen  of  pyroxy- 
line  there  will  be  a  certain  proportion  of  iodide  or  bromide,  and 
a  certain  strength  of  development  that  will  produce  good  results, 
and  these  must  be  found  by  trials.  (See  p.  133.) 

A  serious  difficulty  is  introduced  into  all  photographic  opera¬ 
tions  by  the  variable  nature  of  the  cotton.  It  seems  almost  im¬ 
possible  to  repeat  an  operation  for  making  pyroxyline  twice,  and 
get  identical  results. 

It  will  be  important  to  bear  in  mind  that  whenever  a  very 
considerable  quantity  of  bromide  has  been  used  in  the  collodion 
the  tendency  of  the  deposit  is  to  be  more  crystalline.  A  curious 
result  follows,  that  in  printing  the  plates  show  themselves  to  be 
less  dense  than  they  appear  to  the  eye,  and  consequently  they 
show  less  contrast. 

It  may  consequently  happen  that  such  plates,  whilst  appearing 
to  a -good  judge  to  have  been  developed  exactly  right,  may  yet 
in  printing  yield  flat  and  unsatisfactory  results.  In  changing 


THE  NEGATIVE. 


169 


from  one  formula  of  salting  to  another  it  will  be  important  to 
bear  this  in  mind. 

The  whole  tendency  of  modern  photography  is  to  full  ex¬ 
posures  and  slow,  careful  developments.  It  follows,  from  what 
has  been  already  said,  that  a  full  exposure  absolutely  necessitates 
a  slow  development,  otherwise  the  negative  is  flat  and  tame,  a 
fault  now  much  commoner  than  it  used  to  be  when  brilliancy  was 
more  sought  after  than  half-tone.  In  fact,  some  seek  so  earnestly 
for  masses  of  half-tone  that  they  sometimes  have  no  high  lights 
at  all  in  their  prints :  this  is  a  fault  which,  though  not  as  bad  as 
the  opposite  error,  is  nevertheless  a  fault;  no  contrasts  that  can 
be  produced  on  paper,  as  shown  by  Mr.  Ruskin,  can  fully  repre¬ 
sent  the  ordinary  contrasts  of  nature.  We  are,  therefore,  never 
justified  in  still  farther  contracting  our  means  by  substituting 
half-tone  for  high  lights.  Indeed,  a  certain  quantity  of  high 
light  is  essential  to  give  to  half-tone  its  full  value  and  due  effect. 

Washing  the  plates  should  not  be  hurried,  but  ample  time  be 
given  to  get  rid  of  the  hyposulphite,  especially  with  valuable 
negatives.  A  simple  arrangement  for  supporting  the  plate 
whilst  washing  is  figured  in  the  introduction  at  p.  36,  and  is  spe¬ 
cially  recommended  as  facilitating  a  safe  and  perfect  washing. 

§  6. — Local  Redevelopment. 

It  will  occasionally  happen  that  after  the  deposit  on  a  negative 
has  reached  a  point  such  that,  whilst  the  denser  parts  have  re¬ 
ceived  all  that  they  can  bear  consistently  with  giving  full  detail 
in  the  high  lights  in  the  print  to  be  hereafter  taken,  the  thinner 
portions,  or  some  of  them,  might  advantageously  have  more 
strength,  that  is,  these  thinner  portions,  though  exhibiting  fine 
details  to  the  eye,  may  be  too  thin  to  print  properly.  In  order, 
therefore,  to  bring  the  negative  into  a  condition  to  show  the 
greatest  possible  transparency  of  shadow,  that  is,  a  clear  render¬ 
ing  of  details  in  the  least  illuminated  portions,  it  may  be  very 
advantageous  to  resort  to  a  local  redevelopment. 

This  may  be  performed  either  before  or  after  fixing.  When 
done  before  fixing,  there  is  more  hope  of  adding  to  the  details, 
when  after,  the  operation  can  be  performed  more  satisfactorily, 
because  the  operator  sees  far  better  what  he  is  about.  In.  the 
former  case,  although  details  not  before  visible  may  be  rendered 
visible,  yet  it  is  doubtful  if,  within  the  limits  of  this  operation, 
12 


170 


PHOTOGRAPHIC  MANIPULATIONS. 


detail  so  brought  out  can  be  got  up  to  printing  strength.  The 
proper  hope  of  this  operation  seems,  therefore,  to  be  the  bringing 
of  visible  details,  too  weak  to  print,  up  to  printing  strength,  and 
this  is  better  done  upon  the  fixed  and  washed  negative.  I  shall, 
therefore,  so  describe  it.  It  will  be  understood,  however,  that  if 
preferred,  exactly  the  same  operation  may  be  performed  upon 
the  unfixed  negative,  remembering  that  the  same  precaution  as 
to  light  must  be  then  used  as  in  the  regular  development,  other¬ 
wise  fogging  will  ensue. 

If  the  negative  has  been  allowed  to  dry,  it  will  be  advisable 
first  to  go  round  the  edges  with  India  rubber  dissolved  in  benzole. 
The  film  must  then  be  well  wetted,  the  plate  is  to  be  grasped  by 
the  left  thumb  and  forefinger  at  one  of  its  corners,  and  so  held 
that  those  parts  which  are  already  fully  dense  shall  be  on  the 
side  of  the  plate  farthest  from  the  operator  (in  a  landscape  nega¬ 
tive  this  will  generally  be  the  sky  side);  the  plate  is  to  be  tilted 
a  little,  so  that  this  far  side  will  be  a  little  the  higher,  and  a  solu¬ 
tion  of  pyrogallic  acid,  silver,  and  citric  acid,  such  as  is  usually 
employed  for  redeveloping,  is  to  be  dropped  upon  those  parts 
where  the  additional  deposit  is  needed.  The  plate  being  very 
wet,  this  dropping  of  solution  will  produce  circles  that  slowly 
expand,  and  as  they  cease  to  expand  wash  down  towards  the  edge 
near  the  operator,  by  reason  of  the  tilting  position  given  as  above 
directed.  As  this  takes  place  the  operator  holds  the  plate  under 
the  bath  and  washes  off  the  solution.  If  the  parts  nearest  to  the 
operator  will  easily  bear  the  additional  deposit  that  they  get  as 
the  solution  passes  over  them,  the  operator  proceeds  more  delibe¬ 
rately.  If  they  are  already  pretty  strong,  he  washes  off  almost 
as  soon  as  the  solution  spreads  to  them.  A  few  seconds  suffice 
to  wash  away  the  solution,  when  the  operator  recommences,  and. 
this  is  done  as  often  as  necessary,  even  up  to  six  or  a  dozen 
times. 

By  this  mode  of  proceeding,  spots  and  stains  are  avoided.  If 
the  solution  were  left  to  rest  on  any  one  part,  a  circular  spot 
might  result  which  would  print  lighter.  The  pyrogallic  solution 
can  be  used  pretty  strong,  but  should  be  kept  clear  and  colorless. 
The  whole  operation  turns  on  not  allowing  the  solution  to  be  for 
a  moment  stationary  anywhere,  but  washing  it  off  as  it  ceases  to 
spread,  and  recommencing.  Of  course,  before  washing,  the  greater 
part  of  the  solution  majr  be  first  drained  off  into  the  developing 
vessel. 


THE  NEGATIVE. 


171 


§  7. — After-Intensification. 

The  three  stages  by  which  the  utmost  possible  density  is  ac¬ 
quired  by  a  negative  are — development,  with  iron,  pyrogallic  or 
gallic  acid  ;  redevelopment ,  by  a  second  application  of  either  of 
the  foregoing  reducing  agents,  not  necessarily  or  even  generally 
the  same  as  at  first  employed,  since  iron  is  commonly  followed 
by  pyrogallic  acid ;  and  after -intensification,  which  last  may  be 
effected  in  a  variety  of  different  ways. 

Eedevelopment  maybe  resorted  to  either  before  or  after  fixing, 
and  in  all  cases  is  accompanied  by  an  addition  of  silver  solution. 
After-intensification  is  always  applied  after  fixing,  and  silver  is 
never  used.  The  object  of  redevelopment  is  always  to  add  more 
silver,  without  acting  in  any  way  upon  the  previous  deposit. 
After-intensification  adds  no  silver,  but  always  acts  chemically 
upon  the  original  image,  bringing  it  into  a  new  combination  more 
opaque  to  light. 

When  it  is  intended  to  apply  an  after-intensification,  it  is  not 
usual  to  redevelop  also,  but  to  fix  after  the  first  development. 
It  should  be  thoroughly  understood  by  all  students  in  photo¬ 
graphy  that  after-intensification  is  at  best  the  remedy  either  of  a 
mistake  in  the  exposure,  or  else  is  rendered  necessary  either  by 
a  deficiency  of  illumination,  or  an  exposure  which  for  good 
reason  has  been  greatly  curtailed.  Therefore,  whilst  a  good 
knowledge  of  several  modes  of  intensifying  is  necessary  for  the 
photographer,  he  should  resort  to  them  as  little  as  possible. 
Where  the  exposure  has  proved  much  too  short  or  too  long,  it 
is  generally  better,  when  practicable,  to  take  another  negative. 
It  will  cost  but  little,  if  any,  more  time ;  the  experience  of  the 
first  will  enable  the  operator  to  time  the  second  correctly,  and 
the  probabilities  of  a  fine  negative  are  decidedly  greater.  The 
following  are  the  best  methods  of  after-intensification : — 

Iodine. — When  only  a  little  additional  strength  is  wanted, 
iodine  may  be  employed.  If  a  few  drops  of  tincture  of  iodine 
be  dropped  into  a  quantity  of  water,  the  latter  acquires  a  pale 
sherry  wine  color,  and  if  poured  over  a  negative  gradually 
blackens  it,  or  rather  brings  it  to  an  exceedingly  deep  violet 
black.  The  application  must  be  stopped  at  this  point  by  washing 
off  the  solution  as  its  continued  action  brings  the  plate  to  a  light 
yellow  color.  The  solution  may  either  be  flowed  over  the  plate, 


172 


PHOTOGRAPHIC  MANIPULATIONS. 


replacing  it  with  fresh  as  soon  as  it  loses  its  color,  or  it  may  he 
applied  as  a  bath. 

Care  must  be  taken  that  there  are  no  undissolved  particles  of 
iodine  present,  as  these  may  lodge  on  the  film  and  produce  yellow 
spots.  For  this  reason  many  prefer  to  add  a  little  iodide  of  potas¬ 
sium  to  the  liquid,  which  enables  it  to  keep  more  iodine  in  solu¬ 
tion.  This  combination  may  be  purchased  of  the  druggist,  under 
the  name  of  “  Lugol’s  solution,”  which  may  be  diluted  with 
thirty  or  more  times  its  bulk  of  water  and  used. 

Chlorine. — The  blackening  may  be  equally  well  effected  by 
chlorine.  Make  a  solution  of  bichromate  of  potash,  one  grain  to 
the  ounce,  and  add  to  each  ounce  two  drops  of  hydrochloric  acid. 
This  solution  is  applied  like  the  preceding,  stopping  as  soon  as 
a  uniform  dark  color  is  obtained. 

Corrosive  Sublimate. — If  a  saturated  solution  of  this  substance 
be  diluted  with  ten  times  its  bulk  of  water,  it  may  be  applied 
precisely  like  the  preceding,  and  blackens  the  plateyvery  effec¬ 
tually. 

The  foregoing  applications  all  give  a  moderate  degree  of  addi¬ 
tional  density  to  the  image,  though  the  latter  acts  more  power- 
full}"  in  this  respect  than  the  others.  They  also  act  alike  in  this, 
that  if  their  influence  be  continued  too  long,  the  images,  after 
having  become  black,  become  lighter  again ;  in  the  first  case 
pass  to  a  yellow  shade,  in  the  two  latter,  to  white.  In  this  con¬ 
dition,  the  film  is  in  all  cases  much  less  dense  than  at  first.  In 
this  stage,  however,  they  are  fit  for  additional  treatment,  which 
may  confer  upon  them  a  much  greater  density  yet,  as  follows : — 

Sulphide  of  potassium  will  not  act  much  upon  the  silver  film, 
but  if  by  the  continued  action  of  either  of  the  three  first  methods, 
the  film  has  been  brought  to  the  yellow  or  white  stage,  and  then 
a  dilute  solution  of  sulphide  of  potassium  be  poured  over  it,  the 
image  acquires  an  intense  blackness,  so  intense,  in  fact,  that  all 
middle  tints  may  be  expected  to  disappear.  Nevertheless,  there 
do  exist  cases  in  which  this  treatment  may  be  applied  with  very 
useful  results.  Negatives  of  line-engravings,  especially  such  as 
are  of  the  full  size  of  the  original,  are  often  very  successfully 
obtained  by  developing  only  till  an  ambrotype  is  got,  and  then, 
without  any  redevelopment,  intensifying  in  this  way.  But  it  is 
to  be  said  that,  in  skilful  hands,  equally  good  and  quicker  print¬ 
ing  negatives  of  line  engravings  are  got  by  the  ordinary  develop- 


THE  NEGATIVE. 


173 


ment  and  redevelopment,  though  they  do  not  give  prints  which 
so  easily  tone  to  a  perfect  black  as  those  yielded  by  the  denser 
sort  of  negatives.  Even,  however,  when  these  denser  negatives 
are  wanted,  they  may  be  still  better  obtained  by  the  following : — 

Cyanide  of  Potassium. — When  a  film  has  been  treated  with  cor¬ 
rosive  sublimate  till  the  white  stage  is  reached,  there  is  often  a 
little  veiling  produced,  scarcely  visible  while  the  print  has  this 
light  color,  but  visibly  injurious  after  the  blackening  by  sulphide 
has  been  effected.  The  writer  has  found  it,  therefore,  useful  to 
substitute  cyanide  of  potassium  for  the  alkaline  sulphide.  The 
cyanide  solution  must  be  very  weak,  one  grain,  or  not  exceeding 
two,  to  the  ounce  of  water.  It  must  be  flowed  over  evenly,  or 
applied  as  a  bath,  and  must  be  washed  off  as  soon  as  an  even 
blackness  is  obtained.  A  continued  action  will  cause  the  nega¬ 
tive  to  whiten  again. 

This  treatment  gives  great  intensity,  and,  at  the  same  time, 
keeps  the  transparent  parts  of  the  negative  beautifully  clear. 
For  photographic  operations  in  processes  not  intended  to  give 
half  tones,  it  is  exceedingly  well  suited,  as  well  as  for  all  cases 
where  clean  sharp  contrast  is  a  main  object. 

Scklippe’s  Salt — Scarlet  Negatives. — This  method  of  intensifying, 
which  the  writer  introduced  to  photographic  notice  some  years 
ago,  has  been  largely  used  where  great  increase  of  intensity  is 
needed,  and  with  excellent  results.  The  negative  is  first  treated 
in  either  of  the  three  first  described  methods :  with  iodine,  chlo¬ 
rine,  or  corrosive  sublimate,  until  the  light  stage  is  reached,  and 
then,  after  washing,  a  dilute  solution  of  Schlippe’s  salt  (sulphanti- 
monite  of  sodium)  is  poured  over  it.  The  negative  instantly 
turns  bright  scarlet,  presenting  a  remarkable  and  very  beautiful 
appearance,  and  becoming  very  opaque  to  active  rays. 

The  solution  of  Schlippe’s  salt  should  contain  about  ten  grains 
to  the  ounce,  and  should  be  kept  tightly  corked.  It,  however, 
gradually  deposits  a  precipitate,  but  if  decanted  from  this  it  still 
acts  well.  The  addition  of  a  few  drops  of  liquid  ammonia  pre¬ 
vents  the  precipitate  and  causes  the  solution  to  keep  quite  well. 
In  this  condition  it  does  not  give  the  bright-colored  negatives 
before  spoken  of,  but  beautiful  russet-brown  ones,  which  are  per- 
l  haps  as  non-actinic  as  those  obtained  without  the  ammonia.  The 
color  will  also  be  found  to  vary  a  good  deal  with  the  extent  to 
which  the  first  application  (of  chlorine,  iodine,  or  sublimate  solu¬ 
tion)  has  been  allowed  to  act.  The  full  scarlet  color  is  got  by 


174 


PHOTOGRAPHIC  MANIPULATIONS. 


allowing  the  first  action  to  reach  the  full  light  stage,  and  apply¬ 
ing  the  Schlippe’s  salt  without  ammonia. 

Solution  of  Schlippe’s  salt  is  apt  to  stain  the  fingers  red.  A 
little  weak  solution  of  caustic  potash  or  soda  instantly  removes 
this. 

It  should  always  be  borne  fully  in  mind  that  operations  with 
either  sulphide  of  potassium  or  Schlippe’s  salt  should  be  car¬ 
ried  on  away  from  the  dark  room,  as  the  sulphuretted  hydrogen, 
of  which  a  little  is  diffused  in  the  atmosphere,  may  tend  to  cause 
fogging.  It  is  also  injurious  to  the  health  to  breathe  a  sulphu¬ 
retted  atmosphere,  therefore  a  thorough  draft  should  be  provided 
to  carry  off  such  vapors. 

Permanganate  of  potassium  has  been  highly  recommended  for 
after-intensifying  by  Mr.  Wharton  Simpson.  A  dilute  solution 
is  poured  over  the  plate  till  the  requisite  intensity  is  obtained. 

Uranium  intensifying  is  now  abandoned,  because  the  nega¬ 
tives  rapidly  become  denser  in  printing  till  worthless;  after- 
intensification  with  sublimate  is,  to  some  extent,  liable  to  a  similar 
objection. 

In  such  cases  it  has  been  recommended  to*  expose  them  to  a 
gentle  heat  for  a  length  of  time,  which  treatment  is  said  to  lower 
the  intensity.  In  copies  of  engravings  without  half  tint  (line 
engravings  and  wood-cuts,  but  not  mezzotints,  lithographs,  or 
photographs)  this  increase  of  strength  is  of  little  or  no  disadvan¬ 
tage  ;  in  such  cases,  therefore,  the  mercury  may  be  used  without 
hesitation. 

These  processes  may  be  divided  into  three  classes,  according 
to  the  amount  of  effect  that  they  produce.  For  a  quite  moderate 
increase  of  density  chiorizing  or  iodizing  may  be  used.  For  a 
rather  greater,  but  still  moderate  result,  sublimate  solution  is 
suitable.  When  a  very  decided  increase  is  needed,  chlorizing, 
iodizing,  or  mercurializing,  in  each  case  till  the  light  color  is 
reached,  may  be  resorted  to,  to  be  followed  by  Schlippe’s  salt  or 
sulphide  of  potassium. 

All  the  mercurial  treatments  weaken  the  film  and  render  it 
liable  to  split  in  drying.  If,  therefore,  a  valuable  negative  is  so 
treated,  it  is  a  prudent  course  to  flood  it  with  gum-water  or  solu¬ 
tion  of  gelatine,  the  former  about  30  to  35  grains  to  the  ounce,  * 
the  latter  about  20  to  25.  If  intensifying  is  much  practised  it  is 
well  to  have  a  solution  of  this  sort  on  hand;  it  may  be  made  to 
keep  by  adding  either  creasote  or  carbolic  acid,  one  or  two  drops 


THE  NEGATIVE. 


175 


to  the  ounce.  The  gum  solution  or  gelatine  is  flowed  over  the 
plate  for  half  a  minute,  worked  in,  and  then  poured  off  again, 
and  the  plate  is  reared  up  to  dry.  After  thorough  drying  it  is  to 
be  varnished.  It  has  been  affirmed  that  a  plate  so  treated  can  be 
varnished  cold  without  the  varnish  drying  dead.  On  the  whole, 
the  gum-water  answers  better  than  the  gelatine,  and  does  not 
require  to  be  warmed  to  liquefy  it. 

This  mode  of  operating  has,  however,  the  disadvantage  that 
the  varnish  cannot  penetrate  the  film  of  gum  (or  gelatine)  and 
does  not  reach  the  back  of  the  plate.  And  as  the  gum  and  gela¬ 
tine  have  no  very  powerful  adhesion  to  the  glass,  the  film  is 
liable  to  scale  off. 

To  Intensify  Varnished  Negatives. — The  usual  plan  is  to  remove 
the  varnish  by  soaking  in  alcohol  or  benzole,  whichever  has  been 
used  in  the  making  of  the  varnish  to  be  removed ;  then  apply 
any  of  the  intensifies  already  described. 

The  complete  removal  of  a  lac  spirit  varnish  by  alcohol  is  no 
easy  thing,  portions  of  gum  remain  behind  and  refuse  to  dissolve. 
Some,  therefore,  intensify  without  removing  the  varnish.  Mr. 
Alfred  Hughes’s  method  is  as  follows:  Dissolve  iodine  in  spirit 
varnish,  one  grain  to  the  ounce,  and  varnish  the  plate  with  this 
varnish,  without  removing  the  first  coat.  Drain  it  well  off,  dry, 
and  expose  to  the  light,  when  a  considerable  increase  of  intensity 
takes  place. 

When  the  operation  has  been  performed  by  dissolving  the 
varnish,  the  use  of  an  alcoholic  solution  of  iodine,  two  or  three 
grains  to  the  ounce,  is  to  be  recommended,  and  acts  more  uni¬ 
formly  than  any  aqueous  solution  would.  Care  should  be  taken 
not  to  leave  it  on  too  long,  and  it  must  be  borne  in  mind  that  the 
alcoholic  solution  cannot  be  instantaneously  removed,  like  an 
aqueous  one,  as  it  takes  a  few  seconds  for  the  water  to  moisten 
the  plate  evenly. 

According  to  Mr.  Winter,  the  simple  removing  of  the  glossy 
surface  of  the  varnish  by  a  moderately  strong  alcohol,  so  as  to 
give  it  a  dead  appearance,  like  ground  glass,  greatly  increases 
the  effective  density  of  the  negative.  This  of  course  applies 
only  to  spirit  varnishes,  and  probably  only  to  those  made  of  diffi¬ 
cultly  soluble  resin  like  lac. 


176 


PHOTOGRAPHIC  MANIPULATIONS. 


§  8. — Reducing  Over-developed  Negatives. 

It  will  occasionally  happen  that  a  negative  has  been  over¬ 
developed,  and  when  examined  after  fixing  and  drying,  gives 
evidence  that  it  can  be  expected  to  yield  only  chalky  high  lights. 
This  discovery  may  come  too  late  to  permit  of  retaking  the 
subject,  especially  with  landscape  negatives  taken  away  from 
home,  and  it  should  be  more  generally  known  than  it  is,  that 
such  negatives  can  be  greatly  improved  by  the  following  treat¬ 
ment,  which  the  writer  believes  was  first  suggested  by  Mr. 
Hughes. 

A  wash  of  very  dilute  solution  of  ‘perchlovide  of  iron  is  applied 
to  the  film,  which  must,  of  course,  be  wetted  beforehand.  It  is 
also  better  to  apply  an  edging  of  India-rubber  to  make  sure  that 
the  film  shall  not  loosen,  though  this  is  not  essential.  The  per- 
chloride  of  iron  can  be  got  from  any  druggist  under  the  name  of 
“  muriated  tincture  of  iron.”  It  is  sold  in  solution,  which  must 
be  largely  diluted;  from  ten  to  twenty  times  its  bulk  of  water  will 
be  needed.  The  first  trial  should  always  be  made  a  rejected 
negative.  The  action  is  extremely  rapid.  The  film  apparently 
darkens,  but  on  holding  it  up  to  the  light,  a  welcome  transpa¬ 
rency  will  be  found  in  those  dense  portions  which  previously 
threatened  to  print  without  detail. 

If  the  negative  wants  very  little  reduction  it  will  be  prudent 
to  use  the  solution  still  more  dilute.  In  nine  cases  out  of  ten, 
if  the  perchloride  does  not  give  satisfactory  results  it  will  be 
from  excess  of  strength  in  the  iron  solution. 

This  is  the  only  application  that  has  ever  given  the  writer 
satisfactory  results,  or  that  he  would  think  of  employing.  Its 
merit  lies  in  that  it  does  not  eat  away  the  image,  but  simply 
thins  it,  and  especially  that  its  action  seems  to  be  greatest  upon 
the  densest  part.  Thus  the  objectionable  features  of  the  nega¬ 
tive  are  removed  without  material  injury  to  the  detail.  Nega¬ 
tives  that  must  otherwise  be  totally  rejected  may  in  this  way 
become  serviceable.  This  mode  of  operating  is  suitable  for  all 
negatives  except  those  taken  by  the  bromide  dry  processes. 

Local  Reduction. — Sometimes  one  particular  object  in  a  nega¬ 
tive  will  develop  to  complete  opacity  before  the  rest  has  attained 
printing  density.  In  such  a  case  to  apply  a  treatment  to  the 
whole  negative  would  virtually  destroy  it,  the  thinner  parts  being 
supposed  to  be  just  thick  enough.  It  is  evident  that  if  any  re- 


THE  NEGATIVE. 


177 


ducing  treatment  could  be  applied  to  the  single  object  or  few 
objects  that  are  too  thick,  a  great  advantage  could  be  gained. 

Hitherto,  the  writer  believes,  this  has  never  been  attempted 
successfully,  in  consequence  of  the  treatment  inevitably  extend¬ 
ing  to  the  adjoining  portions  of  the  image.  It  occurred  to  the 
writer  lately  to  try  the  effect  of  sizing  the  film  with  gum  and 
then  applying  the  reducing  agent.  It  was  found  that  this  treat¬ 
ment,  as  foreseen,  resulted  in  making  a  change  in  the  film  similar 
to  that  which  blotting  paper  undergoes  by  sizing,  that  is,  that  a 
solution  no  longer  sunk  into  the  film  and  spread  around,  but  was 
completely  localized  in  its  action  ;  and,  therefore,  that  any  single 
dense  object  could  be  reduced  in  a  quite  remarkable  way. 

The  operation  is  as  follows :  Pour  over  the  plate  (of  course 
before  varnishing)  a  50  grain  solution  of  gum  arabic,  work  it  in, 
and  let  the  plate  dry.  Then  take  some  perchloride  of  iron  (or 
muriated  tincture  of  iron)  and  dilute  it  largely  until  it  is  of  a 
pale  straw  color  only.  Apply  this  delicately  on  the  part  to  be 
reduced,  with  a  small  elastic  sable  brush,  keeping  strictly  inside 
the  limits  of  the  object.  This  presently  diminishes  very  satis¬ 
factorily  in  density,  and  when  a  proper  point  is  reached,  the 
solution  is  washed  off.  It  is  to  be  observed  that  if  the  object 
proves  not  to  have  been  sufficiently  reduced,  a  fresh  coat  of  gum 
must  precede  a  new  application  of  the  reducing  agent,  supposing 
that  the  plate  has  been  washed  off  For  washing  quickly  takes 
out  the  gum,  and  then  the  film  returns  to  its  blotting  and  spread¬ 
ing  condition.  This  mode  of  treatment  is  really  useful. 

§  9. — Negatives  for  Enlargement. 

A  negative  intended  to  be  enlarged  from,  should  always  be 
taken  specially  for  that  purpose.  It  is  undoubtedly  true  that 
some  negatives  taken  for  ordinary  printing  are  capable  of  being 
used  for  enlarging  from ;  such  are  those  that  print  easily  in  the 
shade.  Usually,  however,  it  is  found  better  to  take  negatives 
expressly. 

These  must  be  thinner  than  usual,  but  it  is  not  to  be  supposed 
that  that  thinness  is  to  be  secured  by  a  brief  exposure.  On  the 
contrary,  because  the  development  must  be  short,  the  exposure 
must  be  full,  a  little  longer  than  usually  given,  so  that  the  picture 
may  flash  up  as  soon  as  the  developer  is  poured  over  it ;  and 
then,  after  a  very  few  seconds,  the  plate  is  rapidly  to  be  washed, 


178 


PHOTOGRAPHIC  MANIPULATIONS. 


lest  the  deposit  should  become  too  thick.  Yan  Monckhoven,  who 
is  excellent  authority  on  this  subject,  remarks  that  the  details  in 
the  shadows  should  be  scarcely  visible,  and  the  denser  parts  so  • 
thin  that  one  can  read  through  them,  and  see  the  smallest  objects 
without  difficulty.  Also,  that  negatives  which  are  too  strong  are 
best  reduced  by  plunging  them  into  a  bath  of  one  grain  of  per- 
chloride  of  iron  to  each  three  ounces  of  water  ;  then,  after  wash¬ 
ing,  apply  cyanide,  which  will  reduce  the  .strength.  The  opera¬ 
tion  to  be  repeated  if  necessary. 

The  deepest  shadows  should  be  represented  by  perfectly  clear 
glass.  Veiling  that  would  be  unimportant  in  an  ordinary  nega¬ 
tive,  will  unfit  one  for  enlarging. 

Yarnish  is  objectionable  for  many  reasons.  The  best  results 
are  got  with  negatives  washed  and  dried  without  even  a  solution 
of  gelatine  or  other  preservative.  Some,  however,  do  not  hesi¬ 
tate  to  apply  protectives,  but,  if  possible,  they  are  to  be  avoided. 

§  10. — Retouching  the  Negative. 

Of  late  years  the  retouching  of  the  negative  has  acquired  a 
very  great  importance.  It  has  been  found  that  well  retouched 
negatives  will  give  prints  so  superior  to  those  from  unretouched 
negatives  as  to  receive  a  very  marked  preference  from  the  public. 

It  is  not  every  one  who  can  do  this  work,  and  it  is,  moreover, 
found  to  be  very  exhausting  to  the  eyes,  especially  when  done  at 
night,  by  artificial  light.  It  should,  therefore,  be  always  done 
by  daylight,  on  a  retouching  desk,  or,  for  want  of  this,  a  large 
piece  of  ground  glass  may  be  rested  in  a  somewhat  inclined  posi¬ 
tion,  and  a  looking-glass  placed  under  it,  and  near  to  a  window. 
The  negative  being  laid  upon  the  ground  glass,  all  its  details  will 
appear  distinctly.  The  eyes  should  be  protected  by  drawing 
down  a  curtain  so  as  to  admit  light  upon  the  looking-glass  only. 
In  some  establishments  this  is  more  completely  effected  by  ar¬ 
ranging  a  partition  in  front  of  and  near  a  window.  In  the  parti¬ 
tion  an  opening  is  cut  sufficient  to  let  the  light  upon  the  mirror 
only. 

'  Several  modes  of  retouching  are  practised.  A  soft  Faber’s 
pencil,  BB  or  BBB,  may  be  used,  or  water-color  be  applied 
with  a  sable  pencil.  As  the  varnish  does  not  take  these  applica¬ 
tions  easily,  it  requires  a  preparation.  Some  prefer  to  take  off 
the  glazed  surface  by  rubbing  gently  with  turpentine.  Others 


THE  NEGATIVE. 


179 


take  finely  powdered  cuttle  bone  and  rub  it  gently  with  the  tip 
of  the  finger  until  the  glassy  surface  becomes  mat  and  takes  the 
application. 

Excellent  results  are  got  both  from  the  pencil  retouching  and 
the  water  color.  When  the  pencil  is  used,  it  is  found  advanta¬ 
geous  to  go  over  it  with  a  stump,  such  as  is  sold  by  the  dealers  in 
artists’  materials;  this  softens  and  harmonizes  the  effect,  and 
blends  it  with  the  neighboring  tints. 

Water  color  retouching  has  the  advantage  that  it  is  easier 
altered,  and  that,  if  mistakes  have  been  made,  they  are  easier  to 
rectify.  Experience  shows  that  the  best  results  are  got  by  using 
colors  that  are  rather  transparent  to  the  actinic  rays — blue  or 
neutral  tint.  This  is  to  be  carefully  laid  on  until  the  desired 
effects  are  attained. 

Too  great  a  smoothness  is  not  to  be  sought  for,  as  the  character 
of  the  face  is  removed.  But  as  defects  of  complexion,  freckles, 
pimples,  or  irregularities  of  skin,  are  apt  to  be  exaggerated  in 
photographic  work,  the  removal  of  these  by  retouching  improves 
the  picture  amazingly.  So  that  those  professional  portraitists, 
who  have  judiciously  retouched  their  negatives,  have  found  them¬ 
selves  suddenly  overrun  with  work. 

Retouching  is  especially  useful  in  removing  the  blockiness  and 
want  of  moulding  that  results  from  one  part  of  the  face  printing 
too  light  or  too  dark  in  proportion  to  the  Test.  It  is  evident, 
however,  that  if  a  negative  is  already  too  dense,  retouching  is 
scarcely  applicable,  because  it  can  only  increase  and  not  diminish 
the  opacity  of  the  image. 

The  effect  of  a  retouched  negative  is  almost  always  more  pleas¬ 
ing  and  more  flattering  than  that  of  one  unretouched.  Because 
wrinkles,  deep  folds  at  the  angles  of  the  mouth,  and  lines  under 
the  eyes,  are  all  apt,  in  photography,  to  be  much  more  conspicuous 
than  in  the  face  itself ;  by  retouching  they  are  subdued  to  any 
extent  desired,  and  very  pleasing  and  even  flattering  prints  are 
obtained  from  negatives  otherwise  unsatisfactory.  Practice  and 
some  artistic  skill  are  necessary,  however ;  the  rounded  shape  of 
the  cheeks  must  be  preserved,  and  the  face  be  not  too  much  flat¬ 
tened.  A  little  careful  and  systematic  practice  will  give  an  in¬ 
sight  that  no  directions  can.  It  is  evident  that  the  negative  must 
not  be  too  dense  to  begin  with. 

Another  method  of  retouching  the  negative  is  to  work  upon 
the  back.  As  the  colors  do  not  take  well  upon  glass,  it  is  usual 


180 


PHOTOGRAPHIC  MANIPULATIONS. 


to  apply  a  thin  varnish,  and  then  to  take  its  surface  off  in  the 
same  way  as  directed  for  preparing  the  film  side.  The  interpo¬ 
sition  of  the  glass  causes  the  retouching  to  print  less  sharply  and 
more  softly  than  when  it  is  put  upon  the  face;  there  is  also  no 
danger  of  injuring  the  image.  The  same  modes  of  operating,  the 
black  lead  pencil  or  the  water  color,  may  be  used. 

Still  another  method  is  to  attach  thin  letter  paper  to  the  back 
by  pasting  or  gumming  at  the  edges,  and  then  applying  color, 
&c.,  upon  the  paper ;  this  method  has  been  long  in  use  for  sketch¬ 
ing  clouds  into  the  transparent  skies  of  landscape  negatives. 

For  stopping  out  small  holes,  Indian  ink  is  generally  used. 
A  color  which  contrasts  with  the  negative  is  always  desirable,  as 
it  is  easier  to  see  what  is  done ;  therefore  if  a  negative  has  been 
blackened  by  any  after-intensification,  it  is  more  advisable  to 
touch  out  holes  with  a  red  color.  Vermilion  is  very  effective, 
and  seems  to  stand  the  sun  pretty  well.  The  indefinite  perma¬ 
nence  of  Indian  ink  against  all  action  of  light  is  an  argument  in 
its  favor  that  is  not  to  be  over]ooked. 

To  landscape  work  little  can  be  added  by  retouching,  except 
in  the  way  of  stopping  out  small  holes  or  minute  defects.  If  it 
be  attempted  to  materially  alter  the  lights  and  shades  of  a  land¬ 
scape  negative,  a  peculiar  and  artificial  character  results,  which 
may  perhaps  be  an  improvement  in  the  particular  case,  but  such 
work  can  rarely  be  considered  first-rate.  In  this  is  an  essential 
difference  between  landscape  photography  and  portraiture,  that 
the  best  portraits  are  almost  always  those  that  have  been  skil¬ 
fully  retouched,  whereas  the  contrary  is  the  case  in  landscape  work. 

The  pasting  of  paper  behind  parts  that  are  intended  to  be 
lighter  is  a  well-known  artifice;  but  it  only  answers  well  when 
the  borders  of  the  part  to  be  influenced  are  pretty  well  defined. 
Some  curious  effects  of  light  exhibited  in  this  city  have  been  so 
produced.  A  female  face,  for  example,  is  raised  upwards,  and  a 
beam  of  sunlight  falls  upon  it  from  a  window,  lighting  it  up  in  a 
striking  way.  The  beam  and  the  effect  upon  the  face  are  pro¬ 
duced  by  pasting  thin  paper  on  the  back  of  the  negative,  and 
printing  in  the  shade.  It  is  scarcely  necessary  to  say  that  the 
paper  must  be  selected  with  a  very  even  grain  and  an  absence  of 
the  lightish  dots  so  commonly  found  in  thin  papers. 

Hard  and  blocky  negatives  can  often  be  made  to  yield  materially 
softer  prints  by  printing  under  ground  glass,  as  will  be  more 
fully  explained  in  the  chapter  on  printing. 


THE  NEGATIVE. 


181 


§  11. — Other  Artifices  Connected  with  the  Negative. 

Other  ingenious  operations  have  been  performed  on  negatives, 
either  to  remove  blemishes  or  to  produce  particular  effects.  Thus 
Mr.  Notman,  of  Montreal,  has  produced  prints  in  which  the 
effect  of  falling  snow  is  very  well  represented.  A  white  pigment 
is  mixed  up  with  water  moderately  thick,  is  put  on  a  brush  and 
flirted  over  the  negative  with  a  quick  jerk,  probably  an  “  atom- 
jzer”  would  be  preferable.  Snow-banks  in  these  pictures  were 
made  in  the  studio  of  common  table-salt,  which  also,  when  scat¬ 
tered  over  clothes  and  drapery,  gives  a  very  good  imitation  of 
the  effects  of  snow  caught  in  the  folds.  Clear  ice  was  represented 
by  plate  glass  resting  on  sheet  zinc :  figures  in  skating  attitudes 
were  posed  on  this.  The  positions  of  rapid  skating  motion  were 
obtained  by  supporting  the  model  in  the  desired  position  with 
Sarony’s  apparatus,  the  stem  of  which  was  concealed  behind  the 
leg  of  the  skater  which  touched  the  ice. 

One  peculiarity  of  photography  lies  in  the  opening  it  affords 
for  original  devices  of  all  sorts  by  the  ingenious.  This  seems 
the  proper  place  to  mention  a  few  of  them. 

Ghosts. — This  name  has  been  given  to  prints  representing  a 
shadowy  figure  through  which  all  the  objects  behind  it  are  dis¬ 
tinctly  seen.  Such  pictures  are  obtained  by  causing  the  model, 
after  remaining  standing  or  in  a  chair  for  a  short  time,  to  move 
suddenly  away,  whilst  the  exposure  is  completed  without  him. 
In  such  a  case  it  is  evident  that  the  objects  at  first  concealed  by 
him  will  afterwards  impress  themselves  on  the  film,  and  be 
visible  through  his  figure. 

Doubles. — A  model  may  appear  twice  in  the  same  print  by 
having  a  couple  of  folding  doors  arranged  inside  the  camera,  a 
little  in  front  of  the  film.  One  of  these  being  closed,  the  sitter 
is  taken  on  the  other  half.  This  then  is  shut,  the  other  door 
opened  (the  lens  being  covered  during  the  change),  at  the  same 
time  the  sitter  is  transferred  to  the  other  side,  and  taken  again  in 
some  different  attitude,  as,  for  instance,  offering  a  glass  of  wine 
to  his  double  across  a  small  table.  By  accurate  adjustment  a 
man  is  made  to  shake  hands  with  himself.  The  position  of  the 
doors  causes  them  to  be  very  much  out  of  focus,  so  that  they  do 
not  show  in  the  image. 

Moonlight  Effects. — Although  a  negative  of  the  moon  itself  can 
be  easily  obtained  in  the  camera,  and  although  it  is  affirmed  that 


182 


PHOTOGRAPHIC  MANIPULATIONS. 


a  dry  plate  exposed  under  a  negative  for  a  long  time  to  moonlight 
gives  signs  of  an  image,  yet  nevertheless  the  photographing  of 
objects  illuminated  by  moonlight  is  practically  impossible.  Prints, 
however,  from  under-exposed  and  over-developed  negatives  often 
have  a  resemblance  to  moonlight  views.  For  in  effect  if  we  ob¬ 
serve  a  view  by  moonlight  we  shall  notice  that  there  is  almost  a 
complete  absence  of  diffuse  light.  Objects  in  shadow  are  not 
lighted  at  all.  A  tree  seen  by  moonlight  exhibits  a  bright  mass 
of  light  where  the  rays  fall,  with  a  moderate  detail;  in  the  shaded 
foliage  there  is  absolutely  no  detail  at  all — it  is  a  black  mass. 
Now  these  effects  are  those  that  belong  to  badly-made  negatives, 
with  all  their  worst  faults  of  exposure  and  development.  But 
these  same  faults,  when  intentionally  introduced  and  artistically 
managed,  are  capable  of  producing  very  pleasing  effects.  Ferrier, 
in  Paris,  has  been  particularly  happy  in  some  of  these.  The 
moon  itself  is  produced  by  a  piece  of  paper  pasted  on  the 
negative. 

Mr.  Baker,  of  Buffalo,  gives  the  following  directions :  A  day 
of  floating  clouds  is  selected,  and  when  the  sun  is  low  and  hang¬ 
ing  over  the  water  surface  of  a  river  or  lake,  or  of  the  sea,  the 
camera  is  pointed  towards  it.  At  the  moment  when  a  cloud 
passes  over  the  sun  the  exposure  is  made.  The  time  given  is  of 
course  short,  and  the  result  is  a  “  moonlight  effect.”  The  clouds 
near  the  sun  throw  brightly-illuminated  reflections  upon  the 
water. 

Artificial  Clouds . — In  cases  where  the  sky  of  a  landscape  has 
become  much  thinned  by  solarization,  it  may  admit  of  painting- 
in  clouds.  This  is  done  by  the  application  of  transparent  water 
colors  on  the  back,  in  imitation  of  natural  clouds.  No  small 
skill  with  the  brush  is  necessary  to  produce  good  effects.  The 
description  of  clouds  known  to  meteorologists  as  the  cumulus ,  the 
cumulo- stratus ,  are  those  most  successfully  imitated.  The  photo¬ 
grapher  should  bear  in  mind  that  the  direction  of  light  must  cor¬ 
respond  with  that  of  the  picture,  and  also  that  unless  the  sun  is 
very  low,  heavy  clouds  are  always  darkest  underneath. 

§  12. — Combination  Prints. 

This  term  is  applied  to  the  obtaining  in  one  print  of  effects 
that  cannot  be  secured  in  any  one  negative,  and  which  are,  there¬ 
fore,  taken  on  two  separate  plates  and  combined  together  in 


THE  NEGATIVE. 


'  183 


printing.  Most  commonly  this  is  applied  to  the  introduction  of 
figures  into  landscapes,  in  some  cases  the  figure  being  the  prin¬ 
cipal  subject  and  the  landscape  subordinate ;  in  others  it  is  the 
reverse.  The  means  employed  are  the  same  in  both  cases.  On 
the  plate  upon  which  the  figures  have  been  taken,  everything 
else  is  completely  stopped  out  by  overlaying  it  with  opaque  color, 
so  that  if  the  negative  were  printed  in  this  condition,  it  would 
print  nothing  but  the  figures  upon  a  perfectly  white  ground. 
Next,  upon  the  landscape  negative,  the  portion  of  the  plate 
corresponding  to  the  figures  is  stopped  out  in  the  same  way.  Of 
course  if  this  negative  is  printed  on  silvered  paper  it  leaves  a 
white  space  corresponding  to  the  figures,  and  upon  this  space  the 
figures  can  be  next  printed  from  the  figure  negative. 

The  difficulty  of  course  lies  in  bringing  the  paper  into  the 
exact  position  for  the  second  printing,  that  the  space  left  for  the 
figures  shall  fall  exactly  under  the  proper  portion  of  the  nega¬ 
tive.  To  do  this  requires  a  careful  and  experienced  printer,  and 
the  trouble  must  be  repeated  for  every  print.  This  difficulty  has 
very  much  limited  the  practice  of  composition  printing,  but  is  in 
a  great  measure  obviated  by  the  ingenious  registering  frames  of 
Mr.  Edwards  and  of  Col.  Stuart  Wortley.  A  printing  frame  is 
constructed  in  which  four  small  square  grooves  ABCD,  Fig. 

Fig.  102.  Fig.  103. 


103,  are  cut,  extending  down  to  the  rebate  on  which  the  negative 
rests.  A  piece  of  thin  wood  is  cut  with  four  square  projections 
A'  B'C'  D',  Fig.  102,  exactly  corresponding  to  these  four  grooves, 
so  that  when  this  piece  of  wood  is  let  down,  the  grooves  act  as 
guides  and  bring  it  always  exactly  into  the  same  position.  A 
wooden  screw  S  serves  to  press  on  the  negative  and  keep  it  per¬ 
fectly  steady  and  immovable.  A  piece  of  silvered  paper  has  its 
ends  bent  over  the  piece  of  wood,  as  shown  at  E  and  F,  and 
secured  with  a  little  gum.  When  it  is  intended  to  print,  this 
board  is  put  into  the  frame,  paper  side  down,  the  projections  slide 
down  the  grooves,  bringing  the  paper  always  into  its' proper  po¬ 
sition.  Pads  and  packing  are  put  behind  the  board,  and  the  back 
(which  is  not  shown  in  the  cut)  is  then  fastened  down. 


184 


PHOTOGRAPHIC  MANIPULATION'S. 


Two  frames  of  this  sort  are  provided,  in  one  of  which  the 
figure  negative  is  placed,  in  the  other  the  landscape.  Having 
stopped  out  all  but  the  figures  themselves  in  the  figure  negative, 
a  print  is  taken  on  the  silvered  paper  that  has  been  fastened  to 
the  board.  This  is  transferred  to  the  other  frame,  and  the  por¬ 
tion  of  the  landscape  negative  corresponding  to  the  figures  is 
accurately  marked  and  stopped  out.  This  being  done,  it  is  evi¬ 
dent  that  the  printing  proceeds  without  difficulty  ;  instead  of  a 
very  skilful  hand  being  needed  any  ordinary  printer  can  take  oft* 
hundreds  of  copies  with  perfect  accuracy.  Each  piece  of  paper 
is  secured  over  the  edges  of  the  board  and  is  printed,  first  in  one 
frame  and  then  in  the  other. 

§  13. — Printing  in  Cloud  Skies. 

The  preceding  method  may  be  applied  to  printing  in  clouds, 
but  as  the  same  accuracy  is  not  required,  simpler  means  are  suffi¬ 
cient.  If  the  negatives  have  not  an  opaque  sky,  that  portion  is 
covered  with  opaque  paint  to  render  it  so. 

A  print  is  taken  and  the  sky  cut  carefully  out  from  it  and  re¬ 
jected,  following  as  nearly  as  possible,  but  in  flowing  lines,  the 
outline  of  the  landscape  as  projected  against  the  sky.  This  is 
done  immediately  after  the  print  is  taken  from  the  frame.  Next, 
expose  to  light,  when  the  whole  becomes  perfectly  black,  and  fix 
without  toning. 

A  good  sky  negative  with  suitable  character  of  clouds  and 
direction  of  light  is  taken,  and  the  black  mask  above  prepared  is 
neatly  attached  to  the  back  of  the  sky  negative,  the  white  side 
next  the  glass.  The  sky  negative  is  now  ready  for  use. 

Prints  from  the  landscape  negative,  when  removed  from  the 
printing  frame,  are  placed  under  the  sky  negative,  and  printed 
again.  The  black  mask  protects  all  but  the  sky,  which  receives 
the  cloud  image  from  the  second  negative. 

Printing  of  this  kind  requires,  of  course,  to  be  done  in  the 
shade,  otherwise  the  line  of  the  mask  cannot  be  so  well  concealed. 
This  object  is  best  attained  by  having  a  border  of  sky  in  the 
mask — that  is,  not  cutting  too  close  to  the  landscape.  With 
ingenuity  and  care  beautiful  results  are  got  in  this  way,  and 
effects  can  be  obtained  that,  when  exhibited,  puzzle  even  the 
photographer  who  is  not  acquainted  with  the  mode  in  which 
they  are  accomplished. 


THE  NEGATIVE. 


185 


For  example,  if  a  dead  tree,  or  a  tree  without  foliage,  as  in 
winter,  or  with  but  small  foliage,  showing  the  sky  through  as  in 
early  spring,  stand  well  out  and  detached  from  the  sky,  clouds 
may  be  printed  in  behind  it,  showing  through  the  branches. 
This  is  done  by  cutting  out  all  that  part  of  the  tree  that  is  thus 
open,  along  with  the  sky,  so  that  all  such  part  of  the  tree  is  not 
masked.  The  clouds  are  then  printed  in,  and  as  such  a  tree  pre¬ 
sents  little  or  no  aspect  of  light  and  shade  in  its  slender  branches 
standing  against  a  bright  sky,  the  second  printing  does  not  affect 
it  otherwise  than  to  make  parts  a  little  blacker,  a  result  that  is 
not  injuriously  noticeable  in  the  finished  print. 

A  splendid  effect  is  produced  by  printing  reflected  clouds  in 
water.  It  requires  three  printings.  A  scene  is  chosen  with  a 
wide  expanse  of  water  and  sky.  The  sky  and  water  are  both 
masked ;  the  sky  first  printed  in,  and  then  the  cloud  negative 
turned  over  so  that  what  was  before  the  top,  becomes  the  bottom, 
and  the  film  or  varnished  side  is  away  from  the  paper.  The 
reflection  of  the  cloud  on  the  water  is  thus  obtained  by  printing 
through  the  glass ,  which  gives  it  just  the  amount  of  indistinctness 
wanted,  whilst  every  cloud  and  shade  of  cloud  in  the  sky  is  faith¬ 
fully  rendered  in  the  water.  The  deception  is  so  complete  that 
it  is  difficult  to  persuade  one’s  self  at  first  that  the  whole  was  not 
taken  at  once,  and  the  reflected  clouds  obtained  at  the  same  time 
with  the  real  ones. 

The  same  general  methods  have  been  used  for  obtaining  effects 
much  more  odd  than  pleasing — as,  for  example,  a  card  portrait  is 
printed  of  a  man  standing  before  his  own  tombstone,  with  his 
head  severed  from  his  body,  and  grasped  by  the  hair  with  one  of 
his  hands.  The  trees  and  objects  behind  the  portion  where  his 
head  would  properly  be,  are  all  perfectly  well  made  out,  so  that 
the  deception  is  complete.  This  is  done  by  masking  and  repeated 
printing.  There  are  several  ways  in  which  it  may  be  thus 
managed,  but  the  subject  has  not  sufficient  importance  for  the 
space  the  details  would  occupy. 

§  14. — Negatives  by  Magnesium  Light. 

Some  successful  applications  have  been  made  of  the  magnesium 
light  to  photography.  Thin  strands,  coils,  or  wires  of  that  metal, 
when  set  fire  to,  burn  with  a  splendid  blue  light,  very  rich  in 
actinic  power ;  negatives  may  be  very  well  taken  by  it.  Interiors 
13 


186 


4 


PHOTOGKAPHIC  MANIPULATIONS. 


and  parlor  groups  have  been  photographed  at  night  by  it,  and 
pictures  taken  of  caves,  catacombs,  and  other  places  inaccessible 
to  daylight. 

The  chief  difficulty  in  obtaining  good  interiors  results  from  the 
directness  of  the  light.  If  one  light  be  used,  of  course  the  shadows 
exhibit  a  total  want  of  illumination.  At  least  two  are  necessary, 
and  this  immediately  introduces  the  danger  of  double  shadows ,  an 
evil  which  is  not  known  in  the  carefully  adjusted  light  of  the 
ordinary  glass  room,  and  which  will  require  special  attention  on 
the  part  of  the  photographer.  Objects  must  be  so  placed  that 
only  one  set  of  shadows  shall  be  visible,  and  the  lights  them¬ 
selves  must  also  be  regulated  with  this  view. 

Of  the  two  lamps  used,  one  must  give  the  predominant  light, 
and  the  other  be  used  to  light  up  the  shadows.  The  predominant 
light  should  be,  of  course,  like  the  light  of  the  glass  room,  a  side- 
upper-front  light.  The  other  must  be  lower  in  height,  and  be 
placed  at  the  other  side.  The  predominance  of  the  first  is  secured 
by  burning  twice  as  much  magnesium  in  it,  say  three  to  five  tapers. 

The  writer  has  elsewhere  pointed  out  that  as  the  light  of  the 
magnesium  diminishes  rapidly  as  the  distance  from  the  lamp 
increases,  the  background  must  be  much  lighter,  or  it  will  show 
too  dark  in  the  picture. 

Very  ingenious  lamps  have  been  constructed  for  burning  mag¬ 
nesium,  especially  one  in  which  a  draught  of  air,  kept  up  by  a 
chimney,  is  made  to  enter  in  front,  and  thus  to  keep  the  heavy 
white  smoke  of  magnesia,  which  is  generated  by  the  combustion, 
from  obscuring  the  light.  It  is  affirmed  by  competent  observers, 
that  the  effective  light  produced  by  a  given  quantity  of  magne¬ 
sium  is  nearly  doubled  by  this  simple  contrivance. 

Mr.  Skaife  substitutes  a  pyrotechnic  mixture  burning  with  a 
very  luminous  flame,  a  mixture  of  magnesium  filings,  chlorate 
of  potash,  and  sulphur,  which  he  suddenly  inflames.  The  camera 
has  been  previously  focussed  by  gaslight,  and  is  left  open,  as  the 
gaslight  makes  no  impression.  Then  the  mixture  being  suddenly 
inflamed  gives  an  intense  light  for  a  moment,  during  which  the 
image  is  obtained. 

§  15. — Storing  of  Negatives. 

There  are  three  ways  of  storing  away  negatives,  that  are  in 
common  use — plate  boxes,  shelves  expressly  made  for  plates,  or 


THE  NEGATIVE. 


187 


the  plates  are  wrapped  up  in  clean  paper  in  bundles  of  ten  or 
twelve  each. 

Plate  boxes  are  made  with  either  single  or  double  grooves.  In 
the  latter,  two  plates  are  slid  together  into  each  groove,  back  to 
back.  Much  trouble  arises  from  the  grooves  in  plate  boxes  not 
being  made  deep  enough.  The  plates  vary  a  good  deal  in  size, 
although  nominally  intended  to  be  equal,  and  the  boxes  some¬ 
times  shrink  very  much  ;  so  that  in  some,  after  having  been  made 
some  time,  the  small  plates  will  get  loose  instead  of  being  con¬ 
fined,  and,  in  other  boxes,  the  plates  a  fraction  over  size  will  get 
fast.  It  has  happened  to  the  writer  to  be  obliged  to  force  out 
the  side  of  a  box  to  get  out  a  negative.  All  these  troubles  should 
be  avoided  by  making  the  grooves  deeper.  The  edges  of  the 
groove  should  be  rounded,  not  square. 

Plate  boxes  should  never  be  used  for  putting  wet  negatives 
into,  both  because  the  boxes  should  never  be  wetted,  and  because, 
if  the  washing  has  been  imperfect,  hyposulphite  may  be  intro¬ 
duced.  Nor  should  negatives  just  varnished  be  placed  in  them, 
as  the  edges  of  varnished  negatives  remain  sticky  after  the  face 
is  dry.  Nor  should  “  dry”  plates  be  dried  in  them ;  in  a  word, 
they  are  for  storage  only. 

Shelves  for  negatives  should  be  built  very  strong,  and  are 
better  so  placed  that  the  window  shall  not  be  opposite  to,  but  at 
one  end  of  the  room,  on  the  side  of  which  are  the  shelves,  so  that 
as  they  are  drawn  out  they  can  be  looked  through  to  obtain  the 
one  sought. 

Negatives  wrapped  up  in  paper  have  been  found  to  keep  better 
than  in  any  other  way.  Cases  are  described  in  which  some  of  a 
lot  of  negatives  have  been  stored  in  boxes,  some  wrapped  in 
paper  and  laid  flat,  where  those  in  boxes  have  cracked,  and  those 
in  paper  have  stood  perfectly.  The  reason  appears  to  be,  that 
plates  sliding  separately  into  grooves  are  exposed  to  changes  in 
the  atmosphere  to  a  much  greater  extent  than  those  securely 
wrapped  up  and  pressed  closely  upon  each  other. 

It  is  evident  that  considerable  care  should  be  exercised  in  the 
selection  of  paper  to  be  interposed.  Printed  or  soiled  paper 
should  be  rigorously  excluded.  Blotting  paper  is  too  porous 
and  hygroscopic.  An  ordinary  quality  of  sized  paper,  not  too 
hard  and  stiff,  is  the  most  suitable. 

The  outside  paper  should  be  good,  strong  wrapping  paper. 


188 


PHOTOGRAPHIC  MANIPULATIONS. 


Paper  saturated  with  India-rubber  varnish  would  doubtless  be 
better  than  any  other.  For  amateurs  who  have  but  small  num¬ 
bers  comparatively  of  negatives,  the  plate  box  is  so  much  the 
more  convenient  form  that  it  will  probably  be  always  that  used. 


CHAPTER  V. 

AMBROTYPES  AND  FERROTYPES. 

Although  ambrotypes  almost  belong  to  the  past,  a  few  brief 
remarks  will  be  made  on  the  subject  here  for  the  benefit  of  those 
who  may  desire  to  make  them.  A  really  fine  ambrotype  is  a 
very  beautiful  thing,  but  for  the  most  part,  they  want  contrast 
and  breadth  of  effect. 

An  ambrotype  is  nothing  but  a  thin  negative.  When  a  nega¬ 
tive  is  held  up  to  the  light,  those  portions  on  which  the  light 
has  acted  in  the  camera  are  more  or  less  opaque,  and  the  lights 
and  shades  in  the  original  are  reversed  in  the  negatives. 

But  the  negative  is  formed  of  grayish-white  silver  powder,  so 
that  if  it  be  viewed  by  reflected  light,  and  held  against  a  black 
background,  those  parts  which  looked  dark  by  transmitted  light, 
appear  light  by  reflected,  and  the  transparent  parts,  which  per¬ 
mitted  the  light  to  pass  through  when  viewed  by  transmitted 
light,  look  dark  in  the  ambrotype,  because  their  transparency 
permits  the  black  background  to  be  seen  through. 

Formerly,  a  different  bath  was  thought  necessary  in  the  two 
sorts  of  work.  Now  the  same  is  generally  used,  although  many 
prefer  to  acidulate  it  with  one  or  two  drops  more  of  nitric  acid. 

A  formula  for  collodion  (if  a  special  collodion  be  desired,  which 
is  not  absolutely  necessary)  will  be  found  in  the  Introduction, 
p.  43. 

The  developer  is  the  same  as  for  negatives,  a  little  more  acidi¬ 
fied.  Or,  when  brilliant  whites  are  wanted,  take — 

Sulphate  of  iron .  250  grains. 

Acetic  acid,  No.  8 . half  an  ounce. 

Best  granulated  nitre . 30  grains. 

Water . 20  ounces. 

As  the  bath  becomes  older,  add  a  little  alcohol  to  cause  the 
developer  to  run  smoothly.  If  there  is  any  disposition  to  fog, 


AMBROTYPES  AND  FERROTYPES. 


189 


increase  the  dose  of  acetic  acid.  Stop  the  development  as  soon 
as  the  image  comes  out  enough  to  be  seen  in  light  reflected  from 
the  surface  of  the  plate. 

Where  dead  whites  are  wanted,  omit  the  nitre. 

Melainotypes  and  ferrotypes  are  ambrotypes  taken  on  plates  of 
thin  varnished  iron  instead  of  glass.  The  operation  is  in  all 
respects  similar.  They  may  be  said  to  constitute  the  most  ordi¬ 
nary  and  least  artistic  of  photographic  products. 

Opinions  vary  very  much  as  to  the  best  means  of  getting  good 
results.  The  points  are  these,  that  a  very  clear,  clean  picture 
must  be  got.  This  of  course  is  most  easily  effected  by  the  aid  of 
acid.  The  acid  may  be  applied  in  various  ways.  For  example, 
the  bath  may  be  made  more  acid  than  usual  with  nitric  or  acetic 
acid,  and  used  with  the  ordinary  collodion  and  development.  Or 
an  ordinary  bath  may  be  used  with  a  very  ripe  collodion,  or  one 
to  which  tincture  of  iodine  has  been  added ;  or  a  very  acid  de¬ 
velopment  may  be  resorted  to.  It  naturally  follows  that  whilst 
very  clear  pictures  are  got  in  this  way,  there  is  an  absence  of 
detail  often  observable.  The  right  plan  is  just  to  carry  the 
acidification  far  enough  to  get  clean  glass  in  the  darkest  shadows 
and  no  farther.  Of  course  the  slightest  veiling  is  fatal  to  the 
ambrotype. 

Collodion  made  with  alkaline  iodides  and  bromides  ripens 
quickly;  some  therefore  omit  entirely  the  cadmium  salts  from 
collodion  intended  for  ambrotypes.  Others  employ  cadmium  and 
ammonium  and  add  iodine,  and  others,  as  mentioned  in  the  In¬ 
troduction,  consider  potassium  essential. 

Alabastrine  Positives. — The  body  of  both  the  negative  and 
ambrotype  is  composed  of  nearly  pure  silver,  which  has  a  gray¬ 
ish  tint,  and  is  deficient  in  brilliancy.  This  defect  injures  the 
light  and  shade  of  the  picture,  and  recourse  is  sometimes  had  to 
mercury  in  the  form  of  corrosive  sublimate  to  whiten  them. 

The  following  formula  may  be  used : — 


Corrosive  sublimate . 40  grains. 

Protosulphate  of  iron . 20  grains. 

Common  salt . 15  grains. 

Water . 2  ounces. 


The  first  effect  is  to  make  the  picture  grayer,  but  the  whiten¬ 
ing  soon  sets  in. 


190 


PHOTOGRAPHIC  MANIPULATIONS. 


CHAPTER  VI. 

PORTRAITURE. 

\  1. — General  Arrangement. 

Having  placed  the  sitter  in  an  easy  and  natural  attitude,  and 
with  due  attention  to  the  management  of  light,  as  described  in  the 
next  section,  it  will  not  be  sufficient  to  simply  set  up  the  camera 
before  him  and  take  a  picture.  Care  as  to  the  point  from  which 
the  picture  is  taken  is  of  the  very  highest  importance. 

If,  for  example,  the  camera  is  set  as  high  as  the  head  of  a 
standing  figure,  and  is  directed  at  him  horizontally,  the  head  will 
occupy  the  centre  of  the  plate,  the  body  one-half  of  the  plate 
only.  If  we  move  the  camera  down  so  as  to  be  opposite  his 
middle,  we  shall  get  the  whole  figure  it  is  true,  but  we  get  the 
figure  as  seen  by  an  eye  placed  no  higher  than  the  camera.  The 
shape  of  the  nose  is  altered  and  injured,  the  neck  is  shortened, 
and  the  whole  character  of  the  face  altered. 

From  these  difficulties  we  are  relieved  by  the  contrivances 
already  explained  in  a  previous  chapter,  the  swing-back  and  the 
sliding  front.  We  raise  the  .camera  at  least  as  high  as  the 
shoulders.  The  first  effect  of  this  is  to  throw  the  head  nearly 
into  the  centre  of  the  plate  and  to  cut  off  the  feet.  This  may 
be  remedied — 

1st.  By  inclining  the  camera  downwards.  This  tends  to  dis¬ 
tort  the  vertical  lines,  and  here  the  swing-back  comes  into  play 
and  straightens  them,  or, 

2d.  By  lowering  the  sliding  front.  As  the  front  is  lowered, 
the  image  moves  down  the  plate,  and  takes  its  proper  position. 

This  last  arrangement  has  this  notable  advantage  over  the  first, 
that  the  best  definition,  which  in  the  portrait  lens  correctly 
focussed  is  that  of  the  central  pencils,  is  got  for  the  head,  pre¬ 
cisely  as  if  the  bust  only  were  taken.  In  the  first  arrangement 
the  middle  of  the  body  is  formed  by  the  central  pencils  and 
receives  the  best  definition.  On  the  other  hand,  the  lowering  of 
the  sliding  front  has  this  disadvantage,  that  the  feet  and  lower 
part  of  the  picture  are  then  formed  by  pencils  more  excentric 


PORTRAITURE. 


191 


than  enter  into  any  part  of  the  picture  in  the  other  case.  Each 
method  has  its  advantages  and  evils,  and  in  some  cases  the  one, 
in  some  the  other,  will  be  proper. 

The  swing-back  is  so  valuable  an  adjunct  to  portraiture  that 
no  one  who  has  learned  how  to  use  it  will  ever  willingly  work 
without  it.  It  is  especially  useful  in  sitting  figures ;  without  it, 
for  example,  the  feet  will  always  be  exaggerated  in  size,  and 
clumsy  looking.  It  gives,  in  fact,  a  new  power  to  the  operator; 
the  plan  of  revolving  the  lens  does  not,  as  so  often  affirmed,  answer 
equally  well. 

A  repeating  bach  enables  the  operator  to  make  the  image  of  a 
lens  fall  in  succession  on  different  parts  of  the  sensitive  film,  thus 
with  two  lenses  and  a  repeating  back,  four  or  more  card  portraits 
are  taken  on  one  plate. 

Distance  of  Position. — As  a  large  lens  will  produce  a  small 
head  by  increasing  its  distance  from  the  sitter,  and  conversely,  a 
small  lens  will  give  a  large  one  by  diminishing  it,  the  question 
naturally  arises  as  to  what  are  the  best  conditions  under  which 
to  obtain  satisfactory  results. 

The  impression  of  relief  and  rotundity  is  greatest  with  very 
short  focus  lenses,  and  gradually  diminishes  as  the  size  of  the 
lens  increases,  until  with  lenses  of  30  or  40  inches  focal  length, 
relief  almost  disappears  (also  the  size  of  the  stop  has  much  to  do 
with  it,  a  large  stop  giving  much  more  relief  with  the  same  lens). 

But,  on  the  other  hand,  this  excessive  effect  of  rotundity  and 
relief  is  anything  but  pleasant  in  itself,  and,  still  worse,  it  is 
connected  with  an  effect  of  “  violent”  perspective  which  draws 
the  middle  of  the  face  outwards,  and  in  a  full-face  portrait,  swells 
up  the  nose  and  lips  most  objectionably.  The  effect  is  detestable 
in  those  faces  in  which  the  size  of  the  lips  and  nose  is  as  large  as 
the  rest  of  the  face  will  bear,  the  enlargement  of  them  introduces 
a  disproportion  most  annoying  and  vexatious  to  the  sitter  and 
friends,  whereas  in  another  face  with  thin  lips  and  small  nose,  no 
bad  result  has  attracted  attention,  simply  because  other  circum¬ 
stances  rendered  it  less  obvious. 

It  will  be  well,  therefore,  never  to  place  the  camera  nearer 
than  twelve  feet  from  the  sitter  as  a  minimum,  and  rather  to  ex¬ 
ceed  this  by  using  a  larger  lens  to  make  up  for  increased  distance. 
In  fact,  there  is  but  little  danger  of  getting  too  far  from  the 
sitter  in  any  ordinary  glass  room  ;  the  danger  is  the  other  way. 

Arrangement  of  Accessories. — The  curvature  of  the  field  of  lenses 


192 


PHOTOGRAPHIC  MANIPULATIONS. 


renders  it  desirable  that  objects  around  the  central  figure  should 
also  be  arranged  into  a  counteracting  curve,  and  be  brought 
nearer  to  the  camera  in  proportion  as  they  are  farther  from  the 
centre  of  the  field  of  view.  This  enables  them  to  be  brought 
into  focus  simultaneously  with  main  figure. 

Groups  are  naturally  governed  by  the  same  rules.  Of  course 
a  stiffly  circular  arrangement  is  to  be  avoided,  but  it  will  be 
always  advisable  to  arrange  that  in  a  group  the  most  distant 
head  shall  be  central,  and  those  that  are  farthest  from  the  centre 
shall  be  nearest  to  the  lens.  A  tasteful  arrangement  of  inter¬ 
mediate  heads  and  figures  will  bring  the  whole  into  harmonious 
combination. 

With  groups  the  swing-back  will  be  always  very  valuable, 
especially  in  avoiding  sameness.  For  with  a  swing  on  a  vertical 
pivot,  the  figures  on  one  side  of  the  central  object  may  be  set  as 
far  back  as  the  central  figure,  and  yet  be  brought  into  good  focus, 
provided  that  those  on  the  other  side  are  brought  considerably 
nearer.  The  advantages  of  the  swing-back  will  thus  continually 
make  themselves  apparent,  and  multiply  as  the  photographer  in¬ 
creases  in  familiarity  with  its  applications. 

Relative  Size  of  the  Figure. — It  is  highly  important  to  propor¬ 
tion  the  size  of  the  figure  to  the  size  of  the  whole  print,  and  it 
may  be  said  that  the  size  of  the  figure  is  almost  always  made  too 
small.  For  one  error  in  the  opposite  direction,  ten  are  made  in 
this,  and  the  result  is  always  to  render  the  figure  insignificant 
and  unsatisfactory.  This  remark  applies  to  all  sorts  of  photo¬ 
graphs,  from  vignetted  busts  to  full  lengths.  And  the  smaller 
the  figure  the  more  conspicuous  any  accessories  that  may  be 
present,  until,  in  some  portraits,  they  fairly  eclipse  the  figure 
itself,  so  that  the  idea  is  conveyed  that  the  sitter  is  taking  care  of 
the  large  but  suspiciously  unreal-looking  vases,  tables,  and  carved 
furniture,  which,  rather  than  the  person,  seem  to  be  the  actual 
subjects  of  the  picture. 

It  is  surprising  that  so  little  criticism  has  been  directed  to  this 
almost  universal  fault.  An  examination  of  portraits  by  great 
masters  will  show  a  very  different  system.  The  figure  takes  up 
a  very  large  portion  of  the  whole  surface,  the  accessories  are 
absolutely  subordinate,  and  not  noticed  unless  attention  is  expressly 
directed  to  them. 

No  error  produces  worse  results  than  this  of  making  the  figure 
too  small.  The  sitter  feels  the  unsatisfactory  and  insignificant 


PORTRAITURE. 


193 


effect  of  the  portrait  offered  to  him,  without  understanding  why 
it  is  so,  and  though  he  may  be  unable  to  say  where  the  fault  lies, 
its  existence  is  perfectly  plain  to  him.  The  photographer  is, 
therefore,  recommended  to  avoid  this  mistake  most  carefully. 

2  2. — Management  of  Light.1 

The  play  of  light  upon  the  sitter  must  be  regulated  partly  upon 
certain  general  principles  of  illumination,  and  partly  according 
to  the  needs  of  the  particular  case. 

The  general  principles  are — 

That  there  shall  be  no  cross  light ;  never  shadows  visibly  cast  in 
more  than  one  direction. 

That  the  light  on  the  side  away  from  the  glazing  shall  be  main- 
tained  as  subsidiary. 

That  there  shall  be  no  false  light,  especially  no  false  reflection 
from  the  eyes. 

That  there  shall  be  no  excess  of  illumination  in  some  one  or  more 
parts  of  the  picture,  otherwise  the  eye  will  be  led  away  from 
the  face  instead  of  led  to  it ,  as  takes  place  in  a  judicious 
distribution  of  light  and  shade. 

That  the  shadows,  wherever  they  may  be,  shall  invariably  receive 
a  sufficient  illumination  that  their  details  may  impress  them¬ 
selves  with  strength  enough  to  show  agreeably  in  the  print. 
There  must  be  no  dark  patches  destitute  of  detail. 

That  the  highest  lights  shall  not  be  so  illuminated  but  what  they 
shall  be  full  of  detail.  A  bald  head,  for  example,  must  not 
run  into  a  light  background,  as  is  occasionally  seen.  White 
hair  must  preserve  all  its  details.  The  play  of  light  and 
shade  over  white  garments  must  be  thoroughly  well  pre¬ 
served,  and  all  white  patchiness  rigorously  excluded. 

Conjointly  with  the  above,  two  different  systems  of  illumination 
may  be  used.  There  is  that  almost  universally  adopted,  in  which 
the  effect  of  the  picture  is  made  as  nearly  as  possible  to  imitate 
what  we  commonly  see  around  us.  The  part  of  the  room,  for 
example,  in  which  the  model  sits,  is  made,  in  its  play  of  light 
and  shade,  to  resemble  ordinary  rooms. 

There  is  another  and  very  effective  system  occasionally  used 

1  See  also  chapter  on  the  “  Glass  Room,”  and  that  on  “  Light  and  Shadow.” 


194 


PHOTOGRAPHIC  MANIPULATIONS. 


in  which  some  of  the  effects  generally  produced  by  distinguished 
portrait  painters  in  their  work,  are  imitated.  The  object  of  this 
system  is  to  allow  no  light,  except  that  which  stands  in  some 
definite  relation  to  the  face.  It  was  the  dictum  of  a  celebrated 
painter  that  a  portrait  ought  to  be  two-thirds  dark. 

To  obtain  this  effect  in  photographic  portraits,  a  dark  back¬ 
ground  and  dark  hangings  are  used.  Dark  clothing  is  worn, 
especially  dark  velvets,  whose  play  of  light  is  always  exceed¬ 
ingly  effective  in  photography.  Whatever  of  light  is  permitted 
in  the  clothing  must  11  lead  up  to  the  face,”  that  is,  so  far  as  it  is 
permitted  to  catch  the  eye,  the  eye  must  pass  directly  from  it  to 
the  face.  All  this,  of  course,  is  more  easily  effected  in  women’s 
vestments  than  men’s;  still  the  application  is  not  confined  to  the 
former.  The  borders  of  the  picture  are  all  kept  dark,  and,  in 
fact,  the  shadows  are  accumulated  in  order  that  the  light  may 
tell  as  effectively  as  possible.  When  well  managed,  this  method 
produces  very  striking  and  beautiful  results,  but  it  requires  con¬ 
siderable  artistic  knowledge  and  feeling  on  the  part  of  the  photog¬ 
rapher.  From  the  large  use  which  Salomon,  of  Paris,  has  made 
of  this  style,  it  is  often  called  after  him.  The  “  Berlin  Portraits1,1 
are  made  by  taking  a  piece  of  glass,  coarsely  ground  upon  one 
side,  and  making  the  negative  upon  the  other.  In  this  way  a 
certain  softness  is  got,  somewhat  resembling,  but  inferior  to,  that 
which  is  obtained  by  retouching.  “  Crayon  Portraits ”  are  pro¬ 
duced  by  printing  a  thin  positive  on  glass,  and  laying  this,  film 
side  down,  upon  a  lithographed  sheet,  shaded  in  imitation  of 
crayon  work.  When  well  done,  the  effect  is  good.  The  glass 
positives  for  this  purpose  are  often  enlargements  from  card  nega¬ 
tives — the  enlargements  are  made  in  the  camera.  Others  modify 
the  effects  and  soften  their  paper  points  by  interposing  a  sheet  of 
glass,  of  gelatin,  of  mica,  or  of  tissue  paper  between  the  negative 
and  the  paper ;  in  this  way  are  made  the  so-called  “  Mezzotint 
Prints .”  This  method,  brought  prominently  forward  by  Mein- 
erth,  gives  often  very  pleasing  pictures. 

So-called  Rembrandt  Effects  represent  the  head  against  a  dead 
black  surface,  with  a  peculiar  and  bright  illumination  round  the 
profile,  brightest  on  the  side  away  from  the  spectator.  The  effect 
is  produced  as  follows :  The  lighting  is  as  usual ;  the  sitter  is 
placed  in  the  usual  position.  The  camera  is  moved  partly  round 
so  that  it  somewhat  faces  the  light,  and  thus  the  portrait  shows 
principally  the  side  of  the  face  that  is  farthest  from  the  side  light, 


PORTRAITURE. 


195 


what  shows  of  the  other  side  of  the  face,  viz.,  the  eyebrow  and 
cheek,  is  more  brightly  lighted  than  the  near  side,  the  former 
being  nearest  to  the  light.  The  background  must  send  no  light 
back,  and  is  best  made  of  black  velvet,  which  should  be  rendered 
by  clear  glass.  As  the  camera  is  turned  partly  towards  the  light 
it  will  need  to  be  carefully  shaded,  otherwise  the  brilliancy  of 
effect,  and  entire  blackness  of  the  background  may  be  impaired. 

Finally,  it  is  to  be  observed  that  the  photographer  must  not 
transfer  any  system  of  lighting  from  a  given  lens  to  another  of 
very  different  focal  length.  If  accustomed  to  work  with  a  lens 
of  a  certain  focal  length,  he  finds  occasion  to  change,  it  will  be 
necessary  to  study  a  proper  arrangement  for  the  new  lens.  A 
lens  of  long  focus  will  bear  a  bolder  lighting  than  one  of  short 
focus,  and  for  want  of  it  may  seem  tame  and  flat. 

§  3. — Exposure. 

A  correct  knowledge  of  the  time  of  pose  comes  only  with  long 
practice  and  through  many  failures.  Not  only  does  the  light  of 
the  glass  room  vary  continually  in  strength,  but  different  com¬ 
plexions  and  different  clothing  will  alter  the  needful  time.  More¬ 
over,  the  photographer’s  task  may  be  greatly  increased  in  diffi¬ 
culty  if  a  style  of  clothing,  unsuited  to  the  character  of  the  sitter, 
chance  to  be  worn  by  him  or  her.  It  would,  in  fact,  be  very 
advantageous  if  the  photographer  could  always  direct  in  advance, 
after  personal  observation,  what  description  of  clothes  should  be 
worn  during  the  pose,  for  it  by  no  means  follows  that  clothes 
most  becoming  to  the  wearer  under  ordinary  circumstances  will 
be  most  appropriate  before  the  lens.  The  element  of  color ,  which 
enters  so  largely  into  consideration,  as  to  suitableness  and  effect, 
here  disappears,  and  the  only  question  is  as  to  the  rendition  of 
light  and  shade  on  the  film.  A  photographically  suitable  clothing 
is,  therefore,  not  at  all  one  in  which  the  colors  harmonize  with 
the  character  of  the  wearer,  but  one  in  which  the  photographic 
effect  of  the  color  harmonizes  with  the  photographic  character 
of  the  face  and  hair.  To  get  a  clear  insight  into  this  matter  it 
will  be  necessary  to  begin  by  considering  the  relation  between 
the  skin,  eyes,  and  hair. 

A  clear  white  skin  will,  of  course,  impress  its  image  rapidly 
on  the  film.  If  the  hair  be  fair,  all  will  go  on  well  and  harmo¬ 
niously.  But  if  a  white  skin  be  combined  with  dark  hair,  the 


196 


PHOTOGRAPHIC  MANIPULATIONS. 


exposure  will  have  to  be  more  accurately  timed,  it  must  be  con¬ 
tinued  until  the  details  of  the  hair  are  fully  out,  and  yet  must  be 
stopped  before  the  face  is  overdone.  Conversely,  where  light  or 
white  hair  accompanies  a  red  or  dark  complexion  there  is  danger 
of  the  hair  being  overdone  and  the  details  lost  in  it  before  the 
face  is  duly  taken.  These  are  faults  that  are  constantly  seen  in 
card  portraits,  and  constitute  difficulties  to  be  understood  and 
conquered. 

Dress. — The  clothes  worn  may  evidently  add  a  further  com¬ 
plication  to  such  of  these  difficulties  as  exist,  or  may  produce 
them  where  they  did  not.  Let  us  suppose  that  a  lady  with  dark 
hair  and  complexion  presents  herself  to  be  photographed,  attired 
in  white,  or  light  blue  or  purple.  It  will  follow  that  by  the  time 
that  justice  has  been  done  to  the  face,  the  fine  gradations  of  shade 
in  the  dress  may  be  lost,  or,  if  preserved,  it  can  only  be  by  skill 
and  care. 

The  difficulties  occasioned  by  contrast  are,  however,  now  far 
less  unmanageable  than  they  formerly  were  when  iodide  of  silver 
alone  was  used,  and  we  see  less  tendency  than  formerly  to  black 
spaces  destitute  of  detail,  and  white  ones  perfectly  flat :  these 
blemishes  are  now  comparatively  exceptional,  and  such  work  is 
always  destroyed  by  the  intelligent  photographer  who  prizes  his 
reputation. 

Some  photographers  keep  two  kinds  of  collodion  on  hand. 
One  sort  for  regular  use,  the  other  containing  more  bromide,  to 
be  employed  where  too  much  contrast  is  apprehended,  especially 
where  masses  of  white  drapery  are  to  be  taken,  in  which  case 
the  proportion  of  bromide  may  rise  to  one-half.  For  regular  use 
such  collodions  are  liable  to  the  objection  that  they  yield  thinner 
pictures  and  require  more  redevelopment. 

Nothing  is  commoner  than  for  persons  to  present  themselves 
so  attired  as  greatly  to  increase  the  photographer’s  difficulties. 
Harsh  contrasts,  the  effects  of  which  are  sufficiently  bad  on  the 
persons,  become  almost  intolerable  in  a  picture.  Add  to  which 
the  various  actinic  powers  of  the  different  tints  often  tend  yet 
farther  to  exaggerate  those  contrasts  which  were  before  suffi¬ 
ciently  annoying  to  the  eye.  A  portrait  in  which  the  dress  is 
cut  up  into  checkers  of  light  and  dark,  or  divided  into  parallel 
stripes  with  striking  contrasts,  must  always  be  unsatisfactory  in 
its  character. 

Attempts  not  wanting  in  ingenuity  have  been  made  to  exhibit 


PORTRAITURE. 


197 


in  photographic  specimens  the  actinic  value  of  different  pigments. 
But  these  can  never  be  of  much  help,  and  the  reason  is  obvious. 
Taking  any  color,  let  us  say  Prussian  blue,  let  a  thin  shade  of  it 
be  lightly  washed  over  white  paper,  and  then  a  very  deep  shade. 
Photographing  these,  the  first  will  act  almost  like  pure  white; 
the  second  almost  like  black,  indeed,  if  made  thick  enough,  as, 
for  example,  the  cake  of  paint  itself,  it  will  be  perfectly  black. 
If,  then,  one  color  is  capable  of  impressing  itself  of  all  shades 
from  white  to  black,  the  assigning  to  it  of  any  particular  shade 
of  half  tint,  must  be  purely  arbitrary  and  altogether  deceptive. 
So,  if  we  attempt  to  compare  two  colors,  let  us  say  green  verditer 
and  raw  umber.  If  the  first  be  put  on  lightly,  and  the  second 
thickly,  the  first  will  appear  to  be  the  more  actinic  color,  and 
by  reversing  the  proportion  we  shall  reach  an  opposite  conclu¬ 
sion.  Precisely  the  same  result  will  accompany  the  various 
shades  of  material  used  in  dress.  Experience,  and  intelligent 
observation  of  what  takes  place  in  the  case  of  every  portrait 
taken,  will  soon  give  a  pretty  exact  idea  of  what  effect  any 
given  costume  will  produce  in  the  negative. 

Velvet  Drapery. — Salomon,  the  French  portraitist,  whose  name 
is  always  necessarily  cited  in  speaking  of  photographic  aesthetics, 
avoids  these  difficulties  by  making  appointments,  and  indicating 
to  ladies  what  colors  will  be  most  effective  for  them.  He  also 
provides  velvet  drapery,  with  which  he  frequently  covers  and 
conceals  the  whole  of  the  dress  worn.  The  velvet  which  he  uses 
is  neither  silk,  nor  is  it  black,  but  a  dark  purple  cotton  velvet, 
and  its  effects  are  often  magnificent. 

Posing  the  Sitter. — When  a  whole  sitting  figure  is  represented 
in  profile,  the  point  at  which  the  back  legs  of  the  chair  reach  the 
ground  will  invariably  and  absolutely  need  to  be  supported.  No 
rule  is  so  commonly  violated  as  this,  and  none  with  worse  results, 
for  the  figure  will  always  appear  to  be  slipping  out  of  the  chair, 
because  its  lines  want  their  due  support.  This  it  will  not  be 
always  easy  to  give ;  the  position  is,  therefore,  especially  for  a 
male  figure,  an  objectionable  one.  If  for  any  reason  it  is  espe¬ 
cially  desired,  the  photographer  must  introduce  some  object,  such, 
as  a  stool,  best  with  drapery,  or  characteristic  objects  over  or  on 
it.  With  the  female  figure  the  difficulty  is  less,  for  its  own  dra¬ 
pery  may  be  so  disposed  as  to  give  the  support  required. 

The  position  of  the  head  of  a  standing  figure  with  respect  to 
the  top  of  the  card,  produces  a  very  curious  influence  on  the 


198 


PHOTOGRAPHIC  MANIPULATIONS. 


apparent  height.  If  the  print  is  so  cut  as  to  bring  the  head  very 
near  the  top  edge,  a  great  impression  of  height  is  produced ;  if, 
on  the  other  hand,  the  card  extends  far  above  the  head,  the  figure 
is  dwarfed.  This  effect  is  independent  of  the  position  of  the 
figure  with  respect  to  other  objects  in  the  picture,  and  depends 
chiefly  on  the  cutting  of  the  card  after  it  is  printed.  Therefore 
this  principle  may  be  used  to  improve  the  appearance  of  dwarfish 
or  very  stout  figures,  providing  it  be  not  carried  to  excess. 

Want  of  attending  to  this  effect  produces  in  card  portraits  the 
most  unintentionally  ludicrous  results.  A  man  of  average  stature 
may  be  made  to  look  seven  feet  or  more  high. 

Mr.  Petsch  makes  some  excellent  suggestions  with  regard  to 
the  overcoming  of  difficulties.  Badly  formed  features  he  subdues 
by  the  arrangement  of  the  head :  a  crooked  nose  is  always  most 
striking  when  seen  from  directly  in  front,  therefore  the  head 
should  be  so  turned  that  the  side  with  the  smaller  surface  is  next 
the  camera,  and  the  larger  surface  is  somewhat  foreshortened. 
An  irregular  mouth,  the  line  of  which  is  not  parallel  to  that  of 
the  eyes,  should  be  similarly  managed,  the  straighter  end  of  the 
mouth  is  turned  towards  the  camera,  and  the  drooping  end  is 
seen  less  conspicuously,  and  is  foreshortened.  Those  who  squint 
are  taken  in  profile.  Very  stout  men  are  to  be  taken  in  three- 
quarter  lengths. 

Arranging  the  clothes  has  likewise  much  influence.  Buttoning 
the  coat  adds  breadth  to  the  figure,  opening  it  gives  relief.  Dark 
clothes  diminish  the  size ;  light,  and  especially  white  ones,  increase 
it.  Defects  in  the  head  and  face  may  be  exaggerated  by  inap¬ 
propriate  ways  of  wearing  the  hair.  To  arrange  the  hair  with 
ribbons,  etc.,  at  the  sides,  makes  a  broad  face  broader,  but  relieves 
the  thinness  of  a  long  narrow  one.  A  high  head-dress  exagge¬ 
rates  the  length  of  a  long  neck,  but  relieves  a  broad  face  if  kept 
front,  otherwise  if  set  far  back.  In  profiles  the  hair  should  not 
be  too  flat  on  the  top  of  the  head,  or  a  flat  expression  is  pro¬ 
duced. 


§  4.— Development  in  its  Relation  to  Portraiture. 

Some  assistance  can  always  be  had  in  difficult  cases  by  regu¬ 
lating  the  development.  The  writer  has  attempted,  in  papers 
written  upon  the  subject  of  negative  development,  to  demonstrate 
the  true  character  and  the  rules  by  which  it  is  governed,  and  as 


PORTRAITURE. 


199 


a  correct  understanding  of  this  is  of  much  importance  to  the  por¬ 
traitist,  a  few  words  may  advantageously  be  said  on  the  matter 
here. 

The  stronger  the  developer,  that  is,  the  more  sulphate  of  iron 
it  contains,  and  the  less  restraining  acid,  gelatine,  or  sugar,  the 
more  rapid  will  be  the  precipitation  of  the  metallic  silver  that 
forms  the  picture.  Just  in  proportion  as  the  silver  falls  'more  slowly 
it  is  more  subject  to  the  attraction  of  the  most  strongly  impressed  parts 
of  the  silver.  In  a  slow  precipitation  the  most  strongly  impressed 
parts  of  the  film  will  get  a  larger  proportion  of  the  deposit  than 
in  a  rapid  precipitation.  This  fact,  which  has  been  thoroughly 
established  both  by  theory  and  practice,  is  of  the  highest  import¬ 
ance,  and  is  the  key  to  all  the  peculiarities  of  iron  development 
in  the  wet  way. 

If,  then,  danger  of  a  flat  picture  is  feared,  either  by  reason 
of — 

1.  An  absence  of  contrast  in  the  subject; 

2.  Too  uniform  an  illumination ; 

3.  A  long  exposure; 

We  should  apply  a  weak  developer ,  in  order  to  increase  the  contrast. 

On  the  other  hand,  if  we  have  reason  to  dread  a  harsh  picture 
from — 

1.  Excess  of  contrast  in  the  subject  itself; 

2.  Insufficient  light ; 

3.  Light  badly  controlled,  so  that  it  is  excessive  in  places 

and  insufficient  in  others ; 

4.  Too  short  an  exposure ; 

We  should  apply  a  strong  developer  to  diminish  the  contrast  by  favor¬ 
ing  a  more  equal  deposit  of  silver. 

The  application  of  these  principles  to  special  cases  is  suffi¬ 
ciently  obvious.  If  it  is  evident  that  the  main  difficulty  of  the 
work  to  be  done  will  lie,  for  example,  in  getting  relief  and  form 
into  a  quantity  of  white  drapery,  we  shall  need  a  slow  develop¬ 
ment,  in  order  that  the  faint  shadows  which  are  to  give  life  and 
form  to  the  white  mass,  shall  not  be  overwhelmed  by  a  rapid 
deposit  of  silver. 

But  if,  on  the  contrary,  it  is  specially  desired  to  obtain  detail 
in  deep  shadows,  a  strong  developer  will  force  the  depositing 
silver  to  find  all  the  faint  impressions  in  these  shadows  and 
bring  them  out  on  the  sensitive  film. 


200 


PHOTOGRAPHIC  MANIPULATIONS. 


A  comparison  of  this  section  and  the  former  will  lead  directly 
to  the  sufficiently  obvious  conclusion  that  exposure  and  develop¬ 
ment  stand  to  each  other  in  opposite  relations. 

And  the  general  rule  will  be :  If  all  the  parts  of  the  subject 
are  actinic  and  well  lighted,  give  a  moderate  exposure,  and  use 
developer  No.  1,  p.  162. 

So,  if  all  the  parts  tend  to  be  non-actinic,  or  if  the  light  is  poor, 
give  a  long  exposure,  and  use  the  same  developer. 

But  if  there  is  considerable  contrast  (and  this  is  the  more  com¬ 
mon  case)  so  that  some  parts  seem  to  demand  a  long  and  others 
a  short  exposure,  and  there  is  danger  of  too  much  contrast,  then 
give  a  full  exposure  and  use  developer  No.  2,  p.  162. 

It  is  not  sufficient,  however,  to  endeavor  to  overcome  these 
difficulties,  the  difficulties  themselves  must  to  some  extent  be  re¬ 
moved.  Light  must  be  so  controlled  that  the  illumination  on  the 
actinic  surfaces  must  be  restrained,  and  that  on  the  shadows  and 
non-actinic  portion  must  be  increased  until  the  two  can  suffi¬ 
ciently  be  combined  in  one  development. 

§  5. — Causes  of  Unsatisfactory  Results  in  Portraiture. 

1.  Too  much  Front  Light. 

Excess  of  front  light  produces  flatness.  Light  is  too  equally 
distributed  over  the  projections  and  depressions  of  the  face,  so 
that  these  lose  their  character,  and  the  face  assumes  an  unmean¬ 
ing  expression,  sometimes  even  a  stupid  or  silly  one.  Such  a 
light  also  throws,  as  Schrank  has  well  remarked,  too  much  illu¬ 
mination  on  the  centre  of  the  forehead,  the  ridge  of  the  nose, 
the  chin,  and  the  cheek  bones.  What  is  worse  still,  it  produces 
a  bright  reflection  in  the  centre  of  the  eye,  precisely  where  the 
dark  pupil  properly  appears,  thus  reversing  the  natural  aspect, - 
and  at  times  giving  almost  the  effect  of  blindness.  Of  all  defects 
of  lighting,  excess  of  front  light  produces  the  most  inartistic 
effects,  and  the  most  thoroughly  displeasing  pictures. 

2.  Too  much  Side  Light. 

Excess  of  side  light  produces  a  too  unequal  illumination  of  the 
two  sides  of  the  face,  gives  an  excessive  projection  to  the  nose, 
and  a  hatchet  shape  to  the  face.  The  effect  upon  the  eyes  is 
sometimes  very  curious,  causing  them  to  look  utterly  unlike  each 
other  in  consequence  of  the  difference  in  the  amount  of  light  that 


PORTRAITURE. 


201 


they  receive.  Still,  the  effects  of  an  excess  of  such  light  are  not 
so  bad  as  those  of  excess  of  top  or  of  front  light.  The  best 
effects  require  a  difference  of  illumination  on  the  two  sides,  which 
may  in  skilful  hands  be  carried  to  a  very  considerable  extent. 
Nevertheless,  it  is  easily  overdone,  and  such  attempts  demand 
good  management. 

3.  Excess  of  Top  Light. 

This  error  produces  effects  precisely  the  reverse  of  those  of 
excess  of  front  light;  all  the  features  become  hard  and  project¬ 
ing;  a  heavy  frown  settles  on  the  brow;  the  eyes  appear  deep 
set  and  cavernous ;  the  nose  is  enlarged,  and  any  hollows  about 
the  mouth  are  greatly  and  unnaturally  increased.  A  black 
shadow  is  produced  directly  under  the  chin,  sometimes  almost 
producing  the  effect  of  a  beard. 

4.  Too  even  Illumination. 

It  is  easy  to  fall  into  an  error  the  reverse  of  all  the  foregoing 
by  diffusing  the  illumination  too  generally.  This  is  most  apt  to 
occur  in  operating  under  a  flat,  low  glass  roof,  where  the  light 
comes  in  around  the  sitter  from  a  variety  of  angles  and  direc¬ 
tions.  The  result  is  a  soft,  characterless  picture,  which  finds 
little  favor,  and  deservedly  so,  whilst  at  the  same  time  those 
unacquainted  with  the  subject  cannot  tell  why  the  picture  is  so 
unpleasing,  for  it  is  undoubtedly  like  the  original,  and  there  is 
no  prominent  objection  to  seize  upon.  At  the  same  time  there 
is  the  greatest  of  all  objections,  viz.,  that  the  portrait  is  totally 
devoid  of  merit,  and  gives  the  face  with  its  least  interesting  and 
acceptable  expression.  The  fault  here  spoken  of  is  one  that  has 
received  too  little  attention,  some  photographers  refusing  even 
to  recognize  it,  and  thinking,  when  they  produce  these  pictures, 
that  they  are  doing  creditable  work ;  they  do  not,  however,  find 
the  sitter  or  the  sitter’s  friends  to  agree  very  cordially  with  them. 

5.  Insufficient  Illumination  below. 

When  the  illumination  is  at  the  same  time  chiefly  horizontal, 
and  yet  is  not  carried  low  enough  on  the  side,  it  may  result  that 
whilst  the  upper  part  of  a  sitter  is  well  illuminated,  the  lower 
part  is  not.  There  results  from  this  a  want  of  detail  in  the 
shadows  of  all  the  lower  part  of  the  figure,  a  defect  which  can 
only  be  remedied  by  an  alteration  in  the  system  of  lighting. 

14 


202 


PHOTOGRAPHIC  MANIPULATIONS. 


6.  Insufficient  Light. 

As  it  must  always  be  the  object  of  the  operator  to  work  well 
with  a  short  exposure,  a  deficiency  of  light  is  one  of  the  most 
serious  evils  to  which  he  can  be  exposed.  I  may,  for  example, 
cite  the  case  of  a  photographer  in  this  city,  who,  after  putting  up 
a  complete  gallery,  found  his  light  so  deficient  that  he  was  led  to 
adopt  the  after-intensification  of  his  negatives  with  mercury  as  a 
regular  system — a  bad  and  dangerous  one  every  way,  worse  by 
far  than  even  an  expensive  alteration  in  his  defective  glass  room. 
His  case  was  by  no  means  a  solitary  one.  It  is  far  better,  in 
constructing  a  glass  room,  to  err  by  having  too  much  light,  the 
excess  of  which  is  so  easily  shut  out,  than  to  make  the  opposite 
mistake.  When  the  mistake  has  been  made,  it  is  better  for  the 
professional  photographer  to  recognize  it  at  once,  and  remedy  it 
radically  by  introducing  more  glass  at  any  cost.  In  doing  so, 
however,  he  should  work  neither  at  random  nor  in  a  hurry.  He 
should  first  carefully  ascertain  by  study  in  which  description  of 
light  his  glass  house  is  most  wanting,  and  proceed  with  a  view  to 
remedying  that  deficiency  in  the  introduction  of  the  additional 
glass.  If  his  glass  room  has  abundant  top  light,  it  would  be  folly 
for  him  to  introduce  his  additional  glass  on  the  roof,  and  so  on. 
The  explanations  already  given  will  enable  him  to  detect  in  what 
direction  his  glass  room  tends  to  err,  and  in  arranging  to  admit 
more  light  he  will  be  in  a  position  to  get  exactly  the  kind  of 
light  which  he  most  wants.  Thus,  in  remedying  a  fault,  he  may, 
if  he  takes  care  and  study,  succeed  in  making  his  room  better 
than  if  that  fault  had  not  been  committed,  for  he  may  succeed  in 
distributing  his  light  more  scientifically  than  if  he  had  at  first 
arranged  to  admit  enough.  It  is  in  this,  as  in  so  many  other  cases 
in  photography,  the  man  who  thinks  carefully  first  over  what  he 
wants,  and  chooses,  after  reflection,  that  which  is  best  fitted  to 
afford  the  desired  result,  will  always  in  the  end  succeed.  One 
who  can  only  learn  through  continual  failures,  will  be  weary 
before  he  can  reach  success.  Every  failure  met  with  should  be 
required  to  yield  its  fruit  in  the  way  of  useful  experience ;  and 
this  should  be  made  a  fixed  rule  by  every  photographer. 


PORTRAITURE. 


203 


§  6. — Backgrounds  and  Accessories. 

The  subject  of  backgrounds  is  one  of  no  small  importance  to 
the  portraitist,  and  one  often  of  no  small  difficulty.  Without 
care,  tact,  and  ingenuity,  his  productions  are  apt  to  be  exposed  to 
the  imputation  of  sameness.  Every  one  has  become  thoroughly 
tired  of  the  column  and  the  balustrade,  which  might  as  well  now 
be  banished  once  for  all.  The  heavy  curtain  has  also  been  a 
good  deal  employed,  but  it  is  too  useful  to  be  definitely  dispensed 
with. 

The  end  of  the  gallery  should  be  colored  of  a  soft  bluish  gray, 
and  will  form  a  useful  background  for  taking  groups  of  several 
persons.  Special  backgrounds  usually  consist,  when  plain,  of 
colored  cloth  sold  by  the  dealers,  and  which  is  usually  stretched 
on  a  large  frame  furnished  with  feet,  rolling  on  castors.  These 
are  of  various  shades,  according  to  the  effect  desired.  The  photog¬ 
rapher  will  need  at  least  three — dark,  light,  and  medium.  Yiews 
are  sometimes  sketched  on  canvas  stretched  on  similar  frames. 
Considerable  tact  and  skill  are  necessary  for  the  production  of 
really  good  pictorial  backgrounds. 

Sometimes  a  very  beautiful  effect  is  produced  by  having  the 
upper  part  of  the  plain  background  lighter  than  the  lower.  This 
is  especially  useful  in  the  case  of  three-quarter  figures,  or  those 
which  include  from  the  head  to  the  knees;  the  light  part  is  made 
to  correspond  with  the  head,  gradually  softened  opposite  the 
shoulders  into  the  dark  shade  of  the  rest.  This  calls  attention 
to  the  head  and  throws  it  out,  with  an  effect  which,  when  well 
managed,  is  excellent. 

Another  useful  effect  which  has  attracted  considerable  attention 
of  late  years  is  that  of  inclining  the  background  so  that  either 
side,  right  or  left,  shall  be  nearer  than  the  other,  taking  care  that 
the  screen  is  towards  the  light,  not  against  it.  This  method  of 
proceeding  has  been  very  effectively  employed  by  the  celebrated 
Salomon,  of  Paris,  and  his  mode  of  managing  it  will  be  seen  by 
inspecting  the  adjoining  sketch  of  his  glass  room.  The  sitter  is 
turned  somewhat  towards  the  light,  and  the  camera  stands  in 
the  direction  indicated  by  the  arrow.  The  portion  of  the  back¬ 
ground  nearest  to  the  glazing  receives  the  strongest  light,  which 
diminishes  gradually  towards  the  other  end,  producing  an  agree¬ 
able  effect,  which  may  be  greatly  varied  by  altering  the  position 
of  the  background  and  screens. 


204 


PHOTOGRAPHIC  MANIPULATIONS. 


Fig.  104. 


Fig.  105. 


Large  backgrounds  should  move  on  heavy  castors  made  ex¬ 
pressly  for  the  purpose,  and  running  on  wheels  of  five  or  six 
inches  in  diameter. 

Canopy  Backgrounds.—- The  same  photographer  has  for  some 
years  past  employed  a  peculiar  arrangement  enabling  him  to 
obtain  a  great  variety  of  effects,  and  dispensing  with  the  necessity 

of  employing  blinds  and  curtains. 
As  Salomon’s  work  has  never  been 
surpassed,  his  modes  of  proceeding 
excite  great  interest ;  the  writer 
annexes  a  figure  copied  from  one 
published  in  the  London  Photogra¬ 
phic  News ,  after  a  drawing  commu¬ 
nicated  by  M.  Salomon  himself. 

A  is  a  semicircular  background 
about  8  feet  high,  10  wide,  and  5 
deep,  from  front  to  back.  B  B  are 
folding  wings,  about  4  feet  wide 
each,  hinged  to  the  background. 
C  is  a  corresponding  canopy,  10 
feet  long  and  4  wide,  hinged  to  the 
top.  Another  canopy,  D  D ,  covers 
the  background  itself:  it  is  in  two 
parts,  hinged  at  the  middle.  The  post  E  at  the  back  carries  a 
pulley  at  the  top,  over  which  pass  cords  connected  with  the  differ- 


PORTRAITURE. 


205 


ent  canopies,  and  fastened  at  the  back  so  as  to  be  easily  raised  or 
lowered. 

The  semicircular  background  A  is  covered  with  wall-paper  of 
a  salmon  color  ;  it  has  three  feet,  not  represented  in  the  cut,  which 
carry  large  castors.  All  the  other  parts,  the  wings  and  canopies, 
are  light  frames  covered  with  thin  transparent  white  muslin,  al¬ 
lowing  a  good  deal  of  light  to  pass,  but  softening  any  direct  sun¬ 
light.  At  the  corners,  between  the  wings  and  the  canopy  (7,  the 
muslin  of  the  upper  canopy  is  continued  out,  so  as  to  fill  up  the 
corner ;  this  is  not  represented  in  the  figure. 

The  sitter  is  placed  in  the  centre  of  the  curved  part,  and.  just 
under  the  front  canopy,  by  raising  or  lowering  which  any  desired 
amount  of  soft  and  diffused  top  light  is  obtained.  So,  too,  the 
side  light  is  regulated  by  opening  or  closing  the  wings.  The 
illumination  is  farther  controlled  or  altered  by  turning  the  whole 
contrivance  on  its  castors,  and  thus  exposing  the  open  portion 
more  directly  to  the  light,  or,  on  the  other  hand,  turning  it  away. 
The  curvature  of  the  background  affords  gradation,  and  its  form 
and  depth  tend  to  give  relief  to  the  figure,  and  even  this  may  be 
very  much  modified  by  raising  or  lowering  the  upper  canopies, 
D  D ,  by  which  monotony  and  repetition  of  identical  effects  are 
avoided,  and  every  grade  of  effect,  from  the  lightest  to  the  dark¬ 
est,  is  easily  obtained. 

When  a  full-length  figure  is  to  be  taken,  the  curve  line  of  the 
background  shows  unpleasingly.  A  movable  surbase  or  wash¬ 
board  placed  behind  the  sitter  cuts  off  the  curve  and  removes  the 
difficulty. 

The  advantages  of  this  system  may  be  briefly  summed  up. 
Effectiveness,  as  it  gives  every  variety  of  light.  Adaptability: 
it  may  be  either  used  in  an  ordinary  glass  room,  or  in  a  common 
room,  as  in  the  latter  case  it  takes  the  place  of  blinds,  curtains, 
and  other  machinery.  Economy :  that  in  use  by  M.  Salomon 
cost  him  fifteen  dollars  only.  To  construct  it  two  curved  pieces 
of  wood,  for  the  top  and  bottom,  are  connected  by  thin  upright 
boards,  tongued  and  grooved  into  each  other,  whilst  the  wings 
and  canopies  are  formed  of  light  framework,  covered  as  already 
described. 

Conical  Backgrounds ,  about  which  a  good  deal  has  been  said, 
have  scarcely  answered  the  expectations  that  have  been  raised. 
The  plan,  also,  of  a  front  screen ,  coated  white,  and  interposed 


206 


PHOTOGRAPHIC  MANIPULATIONS. 


between  the  sitter  and  the  camera,  with  an  opening  cut  into  it, 
has  also  proved  unsatisfactory,  in  consequence  of  its  tendency  to 
produce  flatness  of  effect. 

Rotating  Background. — Canvas  is  stretched  over  a  flat  wheel, 
which,  for  lightness,  consists  simply  of  a  round  rim,  connected, 

by  wooden  bars  or  spokes,  with  the 
axle  at  the  centre.  This  canvas  is 
colored  of  a  warm  gray  or  fawn 
color,  shaded  from  one  side  to  the 
other  (see  Fig.  106),  so  that  there 
is  a  distinct  but  moderate  difference 
of  tint. 

This  background  can  be  put  to 
several  uses.  It  may  be  set  with 
the  lightest  portion  uppermost,  and 
used  as  a  graduated  background,  the 
advantage  of  which  has  been  already 
explained,  or  it  may  represent  a 
lighter  shade  on  one  side  of  the  sitter 
than  the  other.  Or,  finally,  it  may  be  made  to  rotate  during  the 
whole  sitting,  and  thus  produce  a  perfectly  even  background, 
with  a  perfection  of  evenness  obtainable  in  no  other  way. 

The  invention  is  ingenious  and  useful,  but  the  writer  considers 
it  susceptible  of  a  great  improvement.  If  a  triangular  sector  be 
cut  out  of  white  paper  and  attached  in  front  of  the  circle,  with 
its  point  at  the  centre,  and  widening  towards  the  circumference, 
then,  if  the  background  be  made  to  rotate,  it  is  evident  that  the 
general  effects  will  be  lightened ,  and  that  in  proportion  to  the 
width  of  the  sector.  Similarly,  by  using  black  paper  the  effect 
will  be  darkened.  It  is  evident  that,  by  having  a  supply  of  these 
black  and  white  sectors,  a  single  wheel  may  be  made  to  produce 
an  endless  variety  of  shades  of  backgrounds,  and  always  exhibit¬ 
ing  a  perfectly  pure  and  even  tint.  All  photographers  know 
how  difficult  it  is  to  obtain  a  plain  background  to  their  portraits 
that  is  absolutely  free  from  blemish. 

Distance  of  Background  behind  the  Sitter. — Four  or  five  feet  is 
a  common  distance,  but  the  practice  varies  much.  Salomon 
makes  his  recede  much  more  than  most,  and  commonly  places  it 
eight  or  ten  feet  back. 

It  is  common  in  photography  to  act  on  the  principle  that  with 
a  plain  and  indefinite  background  no  furniture  shall  be  intro- 


Fig.  106. 


PORTRAITURE. 


207 


duced ;  and  that,  on  the  other  hand,  if  any  furniture  be  visible, 
the  background  shall  correspond  and  complete  the  room.  This 
is,  however,  not  so  absolutely  necessary  as  some  suppose.  For 
example,  if  a  three-quarter  figure  be  represented  standing  at  the 
side  of  a  small  table  and  occupied  in  any  way,  as  with  papers, 
letters,  flowers,  work,  etc.,  the  picture  may  be  finished  with  a 
plain,  or,  better,  a  simple  shaded  background,  such  as  just  de¬ 
scribed,  and  thus  the  photographer  is  relieved  from  the  incessant 
use  of  a  limited  stock  of  combinations. 

It  is  a  most  serious  mistake  to  crowd  quantities  of  objects,  such 
as  vases,  urns,  bouquets,  etc.,  into  the  picture.  This  only  results 
in  distracting  and  confusing  the  attention.  Certain  points,  where 
lines  of  direction  reach  the  floor,  or  a  table,  or  other  object,  often 
need  imperatively  to  be  supported  by  some  object ;  this  part  of 
the  subject  will  be  treated  of  more  particularly  hereafter.  A  fore¬ 
ground  is  often  relieved  by  characteristic  objects,  grouped,  not 
scattered.  But  then  they  require  to  be  handled  with  taste  and 
according  to  rule,  and  must  never  be  strewn  about  or  huddled 
together  promiscuously.  Particular  care  should  be  taken  to 
avoid  brilliant  reflections  of  light  from  accessories,  and  for  this 
reason  such  objects  should  have  dead,  and  not  reflecting  surfaces. 
Anything,  in  fact,  that  tends  to  make  them  conspicuous,  distracts 
the  attention  from  the  figure  itself. 

In  some  photographs  the  figure  itself  is  quite  a  subordinate 
affair,  being  completely  subdued  by  dazzling  furniture  and  by 
crowds  of  vases,  bouquets,  and  other  objects,  placed  in  the  most 
unnatural  and  improper  positions.  Sometimes  the  very  first 
thing  that  catches  the  eye  is  the  pattern  of  the  carpet,  composed 
of  ill-assorted  figures  and  inharmonious  lines.  Such  mistakes  as 
this  last  are  doubly  unfortunate,  as  they  tend  to  repeat  themselves 
through  a  large  part  of  the  photographer’s  work.  Generally 
speaking,  any  object  that  must  appear  in  many  pictures  should 
be  extremely  inconspicuous,  and  this  holds  with  nothing  more 
than  with  the  carpet,  if  there  is  one. 

A  vignetted  bust  undoubtedly  possesses  advantages  over  any 
other  description  of  photographic  portraiture  :  it  is  that  form  in 
which  the  shortcomings  of  our  methods  are  best  overcome.  It 
may,  therefore,  be  doubted  whether,  in  the  introduction  of  the 
cabinet  size,  it  has  been  wise  to  endeavor  to  exclude  the  vignette. 
The  whole  plate  vignette  heads  which  were  formerly  made,  and 


208 


PHOTOGRAPHIC  MANIPULATIONS. 


are  now  so  rarely  seen,  were  far  more  effective  than  the  little 
card  heads  that  have  taken  their  place. 

When  pictorial  backgrounds  are  employed,  it  is  necessary  that 
the  lens  should  be  directed  at  the  point  of  sight,  that  is,  at  the 
point  to  which,  in  the  drawing  of  the  background,  the  spectator’s 
eye  was  supposed  to  be  directed,  namely,  the  point  at  which  the 
line  of  vision  cuts  the  horizon.  If,  as  may  happen,  this  point  is 
not  very  easily  distinguishable,  the  lens  should  at  least  be  di¬ 
rected  at  the  horizon  line  of  the  picture.  Or,  what  is  still  better, 
the  horizon  line  should  be  completely  concealed  by  a  skilfully 
arranged  design.  If  neither  of  these  precautions  be  adopted,  there 
will  be  no  illusion  whatever,  and  this  is  why  the  effect  of  fanciful 
backgrounds  is  so  rarely  good. 

Good  effects  may  be  obtained  by  using  a  background  of  brown 
paper,  shading  it  off  with  white  crayon  in  a  light  and  sketchy 
way.  If  it  be  desired  that  the  print  shall  show  parallel  strokes 
of  shading  over  the  shoulders  and  round  the  head,  in  imitation 
of  crayon  drawing,  it  is  evident  that  this  result  can  be  attained 
by  marking  on  the  background  a  central  spot  for  the  head,  and 
sketching  large,  coarse  shading  around  it.  In  this  case  black 
crayon  or  charcoal  should  be  used  on  a  light  buff  ground.  Such 
backgrounds  will  need  to  be  in  sliding  frames,  balanced  with 
weights,  that  they  may  be  raised  or  lowered  to  bring  the  centre 
into  exact  correspondence  with  the  head. 

The  appearance  of  the  g^ain  of  drawing-paper  is  sometimes 
given  to  the  finished  and  mounted  photograph  by  passing  it, 
before  quite  dry,  through  a  press,  together  with  a  piece  of  coarsely 
grained  paper  laid  on  the  surface  of  the  print. 


CHAPTER  VII. 

LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY. 

§  1. — General  Remarks. 

Landscape  photography  is  a  very  fascinating  pursuit;  and 
when  once  undertaken  in  good  earnest,  and  pursued  to  successful 
and  satisfactory  results,  is  not  often  or  easily  abandoned. 

The  first  need  will  be  to  possess  a  good  camera  and  good  lenses. 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  209 


The  subject  of  lenses  having  been  already  discussed,  the  writer 
will  here  simply  repeat  his  conviction  that  for  views  which  do 
not  include  architectural  subjects,  the  view  lens  is  not  easily 
excelled,  at  least  when  its  too  small  angle  of  view  is  remedied 
as  in  Dallmeyer’s  wide-angle  view  lenses.  Used  with  equal 
stops,  these  lenses  have  greater  depth  of  focus  than  any  others 
that  the  writer  has  tried.  The  Steinheil  aplanatic  gives  very 
harmonious  landscapes  and  renders  architectural  lines  correctly. 

It  is  important  to  repeat  here  that  the  best  effects  will  never 
be  obtained  with  lenses  of  too  small  focus.  Under  their  influence, 
landscapes  become  so  altered  as  to  be  unrecognizable.  Buildings, 
in  place  of  seeming  to  stand  upon  a  firm  foundation,  seem  to  totter 
forwards.  Rectangular  corners  are  made  to  assume  the  appear¬ 
ance  of  sharp  angles,  so  that  the  building  no  longer  appears 
square,  but  lozenge-shaped.  The  upper  corners  of  the  roof  look 
high  and  peaked,  and  the  real  character  of  the  edifice  is  lost. 

Levelling  the  Camera. — When  architectural  subjects  constitute 
the  picture  or  are  included  in  it,  the  camera  must  always  be 
levelled,  or  the  lines  of  the  building  will  not  be  straight  in  the 
image.  The  level  may  be  either  rested  on  the  camera,  or,  what 
is  better,  it  may  be  countersunk  into  the  camera,  and  so  remain 
permanently  attached  to  it.  To  make  this  arrangement,  the 
camera  should  be  placed  on  a  perfectly  level  surface,  ascertained 
to  be  such  by  careful  levelling.  The  “universal  level,”  which  is 
round,  and  about  an  inch  or  an  inch  and  a  quarter  in  diameter, 
is  then  permanently  fastened  into  its  opening  with  shellac  cement, 
and  so  placed  in  it  that  the  bubble  shall  be  central. 

Of  course,  where  a  building  is  so  unfortunately  situated  that  a 
view  cannot  be  obtained  except  with  a  very  short  focus  lens,  its 
use  will  be  excusable,  but  the  result  will  never  be  satisfactory. 

It  sometimes  happens,  also,  that  buildings  in  narrow  streets 
cannot  be  photographed  except  from  the  second  or  third  stories 
of  opposite  houses.  Such  pictures  are  inferior  to  those  obtained 
from  the  ground,  and  always  give  the  idea  of  being  taken  from 
some  unnatural  point  of  view.  It  is  unfortunate  that  buildings 
in  cities  are  general^  so  situated  that  no  first-class  photograph 
can  be  obtained  of  them,  owing  to  the  narrowness  of  streets  and 
crowding  of  houses. 

With  landscapes  this  levelling  is  less  necessary.  To  obtain  a 
perfectly  truthful  representation,  it  is  essential,  and  therefore  no 
view  can  be  accepted  as  giving  an  accurate  delineation  of  scenery 


210 


PHOTOGRAPHIC  MANIPULATIONS. 


■unless  the  camera  was  levelled  when  it  was  taken.  But  in  taking 
views  simply  as  beautiful  objects,  more  latitude  may  be  allowed. 

§  2. — Choice  of  Conditions. 

As  landscapes  are  always  seen  with  disadvantage  under  a  noon¬ 
day  sun,  so  photographs  taken  under  similar  circumstances  are 
mostly  unpleasing ;  and  as  photography  tends  to  exaggerated 
contrasts  of  light  and  shade,  the  result  is  all  the  worse.  Many 
experienced  landscape  photographers  therefore  avoid  bright  days, 
and  like  best  of  all  those  times  when  the  sky  is  covered  with 
white  clouds  through  which  the  sun  occasionally  breaks.  If  a 
glimpse  of  sun  can  be  secured  at  the  end  of  an  exposure,  the 
best  of  all  effects  is  got,  and  this  may  be  compared  to  the  effect 
in  nature  of  the  softened  sun  late  in  the  afternoon,  and  we  all 
know  the  magical  influence  of  such  light  even  upon  the  tamest 
of  scenery.  It  is  therefore  a  good  plan,  if  there  is  hope  of  a 
burst  of  sun,  to  cover  the  lens  a  little  before  the  proper  exposure 
has  been  given,  and  then,  when  the  sun  comes,  to  expose  for  a 
moment,  and  so  light  up  the  picture  without  getting  harsh  con¬ 
trasts.  These  last  may,  in  extremely  bright  weather,  give  an  effect 
of  snowiness  in  the  high  lights,  which  is  in  the  highest  degree 
displeasing. 

The  time  during  which  the  lens  may  be  covered  to  wait  for 
this  sun  will  depend  upon  the  weather.  In  moist  or  cool  weather 
much  more  time  may  be  prudently  allowed  than  in  hot  or  dry. 
Great  care  should  be  taken  not  to  disturb  the  camera  in  opening 
and  closing.  For  this,  the  morocco  lined  with  velvet  caps,  now 
furnished  with  all  the  best  lenses,  are  very  recommendable,  and 
work  better  than  the  common  brass  caps. 

As  the  sky  is  apt  to  be  over-exposed,  it  may  often  be  advan¬ 
tageously  shaded  during  part  of  the  exposure.  This  may  be  done 
by  holding  the  hand  or  other  object  in  front  of  the  upper  part 
of  the  lens,  and  near  to  it,  moving  it  continually.  To  accomplish 
the  same  object,  sky-shutters  are  often  made  to  the  lens  or  to 
the  camera,  but  it  is  difficult  to  use  them  without  disturbing  the 
camera.  In  landscape  taking,  the  photographer  will  avoid  the 
use  of  the  two  smaller  stops.  The  object  of  the  stop  should  be 
clearly  understood.  In  the  case  of  the  view  lens,  it  is  to  obtain 
depth  of  focus,  to  have  the  distant  and  the  moderately  near 
objects  simultaneously  in  focus.  With  the  doublets  and  the 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  211 


view  lens,  diminishing  the  size  of  the  stop  improves  the  defini¬ 
tion  and  crispness  at  the  margin.  When  these  objects  have  been 
sufficiently  attained,  no  further  diminution  of  the  stop  is  advisable, 
as  the  image  loses  in  character  and  boldness,  in  addition  to  which 
the  time  of  exposure  is  of  course  increased. 

All  the  most  experienced  photographers  are  agreed  that  a  view 
should  invariably  be  taken  with  the  largest  stop  that  the  condi¬ 
tions  of  the  case  will  permit.  As  soon  as  a  satisfactory  definition 
is  obtained,  further  reduction  of  the  stop  should  be  avoided  with 
the  utmost  care.  A  small  stop  produces  a  flat  picture,  without 
gradation  of  distance  or  atmosphere.  A  large  one  gives  a  bold, 
clear  view,  with  the  objects  in  the  respective  planes  of  distance 
well  made  out.  Objects  that  with  a  small  stop  seem  pressed 
together,  with  a  large  one  stand  well  out  and  show  what  they  are. 
The  photographer  cannot  be  too  strongly  enjoined  not,  in  order  to 
obtain  a  microscopic  sharpness,  to  sacrifice  the  general  character 
and  expression  of  his  view.  Of  course,  good  definition  cannot  be 
dispensed  with.  But  when  the  operator  finds  that  he  cannot  get 
this  without  a  very  small  stop  in  using  any  of  the  ordinary  forms 
of  lenses,  he  may  be  sure  that  he  is  straining  the  lens,  making  it 
do  work  for  which  it  is  unsuited,  and  therefore  that  he  cannot 
expect  the  best  results. 

A  photographer  may  visit  scenes  of  great  natural  beauty,  and 
may  be  deeply  impressed  by  them.  He  may  labor  very  hard  to 
reproduce  them  in  his  negatives,  and  yet,  after  much  effort,  he 
may  obtain  but  unsatisfactory  results.  Some  will,  under  these 
circumstances,  lay  the  blame  on  photography,  and  affirm  that  the 
indifferent  results  spring  from  the  incapacity  of  the  method  to 
yield  what  is  wanted.  Others  will  not  perceive  the  deficiencies  of 
their  own  pictures,  and  think  they  have  all  that  can  be  expected; 
whilst  others,  again,  with  a  truer  sense  of  the  beautiful,  will  be 
disheartened  by  the  difference  between  what  they  have  seen  in 
nature  and  what  they  have  been  able  to  carry  away.  But  this 
is  in  reality  the  first  step  towards  ultimate  success.  A  keen 
appreciation  of  errors  and  imperfections  gradually  helps  to  avoid 
them,  but  not  without  many  failures  and  much  persistent  effort. 

In  viewing  a  landscape  in  nature,  the  eye  is  apt  to  seize  and 
rest  upon  the  characteristic  features,  overlooking  those  that  are 
secondary.  A  lens  cannot  do  this,  and,  singularly  enough,  the 
eye  will  not  do  that  with  a  picture  which  it  will  with  real  objects, 


212 


PHOTOGRAPHIC  MANIPULATIONS. 


but  insists,  as  it  were,  that  the  picture  should  represent  them  as 
they  should  be.  This  fact  is  so  conspicuously  true,  that  examples 
are  scarcely  necessary.  They  will,  however,  continually  present 
themselves  to  the  photographer.  Perhaps  the  view  lies  in  a  wild 
valley  in  the  midst  of  hills,  and  the  scene  is  not  marred  by  the 
presence  of  a  rustic  cottage.  But  perhaps  beside  -it  are  lines 
hanging  full  of  clothes  drying.  This  the  eye  passes  over  and 
excuses  in  the  scene  itself ‘  but  the  same  feature  introduced  into 
any  picture,  photographic  or  otherwise,  provokes  inextinguishable 
laughter. 

So  with  the  hideous  telegraph  poles  that  line  all  our  roads  and 
railroads,  and  intrude  into  almost  all  our  scenery.  The  eye  con¬ 
sents  reluctantly  to  forget  them  by  an  effort,  and  to  consider  the 
scene  without  reference  to  them,  and  to  some  extent  succeeds. 
But  in  the  photograph  they  come  out  straight,  stiff,  and  promi¬ 
nent.  Even  the  wire  is  perfectly  made  out.  It  results  that  often 
a  scene  cannot  be  taken  from  its  best  points  by  reason  of  these 
detestable  adjuncts,  and  that,  because  of  their  continued  repe¬ 
tition  at  short  intervals,  the  effort  to  wholly  exclude  them  be¬ 
comes  totally  unavailing.  Telegraphs  are  necessary  things,  but 
there  is  no  reason  that  they  should  be  permitted  to  intrude 
through  scenery  of  recognized  natural  beauty.  This  is  carrying 
utilitarianism  too  far,  and  would  be  tolerated  in  no  country  less 
corporation-ridden  than  ours.  Six  miles  of  the  scenery  of  the 
beautiful  Wissahickon  are  in  this  way  marred  by  the  poles  that 
carry  a  wire  apparently  for  individual  convenience,  which  might 
better  dispense  with  it,  or  choose  another  route. 

As  the  camera  has  not  the  painter’s  power  of  excluding  or 
subduing  intrusive  objects,  all  that  the  photographer  can  do  is 
to  endeavor  so  to  select  his  point  of  view  as  to  avoid  them.  This 
is  a  matter  that  deserves  more  pains  to  be  taken  than  it  mostly 
receives.  After  the  view  has  been  taken,  it  will  sometimes 
be  found  that  a  change  of  position  of  even  a  few  yards  only 
would  have  made  a  material  improvement ;  a  discovery  morti¬ 
fying  and  annoying,  and  better  avoided  by  a  careful  search  be¬ 
forehand. 

A  question  will  often  present  itself  as  to  whether  any  particu¬ 
lar  view  will  give  the  best  effect  if  taken  on  a  plate  with  its 
longest  side  vertical  or  horizontal.  The  writer  has  elsewhere 
pointed  out  that  this  question  is  best  answered  by  observing  what 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  213 

is  the  direction  of  the  principal  object  in  the  landscape,  and  making 
the  greatest  dimension  of  the  plate  correspond  with  it. 

Thus,  a  dam  will  for  the  most  part  look  best  in  a  wide  picture, 
whilst  for  a  narrow  and  high  waterfall  the  greatest  length  of  the 
plate  should  be  up  and  down.  So,  too,  where  the  chief  object  is 
a  tree  or  a  group  of  trees ;  whereas  with  a  bridge  the  principal 
dimensions  should  be  right  and  left.  But  no  such  rules  can  be 
an  absolute  guide,  it  will  only  aid  in  deciding,  and  if  any  doubt 
is  felt,  an  excellent  plan  is  to  try  it  both  ways ;  on  inspecting 
the  prints  no  doubt  will  remain  as  to  which  was  the  best  position, 
and  the  comparison  will  aid  in  forming  a  correct  judgment  on 
subsequent  occasions. 

In  a  landscape,  the  best  effects  are  to  be  secured  by  contrast.  In 
photography,  as  we  have  no  effects  of  color,  our  contrasts  are 
limited  to  those  of  line  and  those  of  light. 

Contrasts  of  line  or  form  are  always  relished  by  the  eye.  The 
effect  of  the  mountain  is  enhanced  by  the  levelness  of  the  plain 
at  its  base.  A  picture  that  should  represent  a  plain  with  no 
elevation,  or  simply  an  elevation  with  no  plain  to  contrast  with 
it,  will  always  be  deficient.  Other  and  beautiful  contrasts  of 
line  are  often  seen  in  a  rolling  country,  even  where  there  is  no 
plain  and  no  great  elevation. 

Contrasts  of  light  and  shade,  technically  called  chiaroscuro,  are 
the  life  of  all  pictorial  representations.  They  give  us,  in  a  great 
measure,  our  ideas  of  the  form  and  relative  position  of  bodies. 
Negatives  taken  in  dull  weather  are  necessarily  deficient  in  this 
quality,  whilst  those  taken  in  clear  sunshine  often  present  con¬ 
trasts  too  harsh.  A  weak  sun  often  gives  beautiful  effects,  and 
as  the  sun  is  less  powerful  when  low,  this,  as  well  as  many  other 
advantages,  is  obtained  by  working  at  such  times. 

Whilst  contrast  is  all-important  in  photography,  it  is  to  be 
carefully  remembered  that  too  much  of  it  is  even  worse  than  too 
little. 

If  a  negative  betaken  with  insufficient  exposure,  and  then  this 
be  attempted  to  be  made  up  in  the  development,  it  will  most 
frequently  happen  that  the  silver,  instead  of  being  deposited  so 
as  to  keep  the  regular  graduation  of  tone,  falls  too  much  upon 
the  lights.  Thus  the  picture  becomes  hard ,  and  if  the  fault  has 
been  great,  it  becomes  snowy. 

In  some  classes  of  subjects,  snowiness  is  not  easily  avoided. 


214 


PHOTOGRAPHIC  MANIPULATIONS. 


If  a  landscape  be  in  part  very  brightly,  and  in  others  very  badly, 
lighted,  the  photographer  finds  himself  in  the  dilemma  that 
either  he  exposes  and  develops  too  long  for  the  one  part,  or  too 
briefly  for  the  other.  In  printing  his  negative,  he  may  find  an 
absence  of  detail,  accordingly,  either  in  the  lights  or  shadows. 
This  difficulty  is  inherent  to  the  nature  of  the  subject,  and  may 
be  too  great  to  be  overcome.  The  best  advice  that  can  be  given 
is  to  give  a  full  exposure,  compensating  for  this  by  using  a  rather 
weak  developer,  and  letting  it  lie  quietly  on  the  surface  of  the 
plate,  without  sending  it  to  and  fro.  The  collodion  should  con¬ 
tain  a  rather  full  proportion  of  bromides.  This  checks  contrast, 
so  much,  indeed,  as  to  render  such  collodion  unsuitable  for  views 
in  which  the  contrasts  are  less  striking.  Some  careful  operators 
carry  with  them  two  sorts  of  collodion,  using  the  most  highly 
bromided  for  mastering  contrasts.  Those  who  are  not  willing 
to  take  this  trouble,  find  themselves  obliged  to  avoid  such  com¬ 
binations,  and  to  return  to  them  in  sunless  weather.  Where 
much  bromide  is  used,  it  should  always  be  borne  in  mind  that 
the  negatives  will  prove  in  printing  more  transparent  than  they 
appear  to  the  eye. 

In  taking  views  along  streams  with  high  banks,  and  in  ravines, 
the  contrasts  of  light  and  shade  will  always  be  really  greater 
than  they  appear  to  be,  and  due  allowance  must  always  be  made 
for  this.  In  such  places  the  shadows  are  apt  to  be  very  dark, 
because  so  much  of  the  sky  is  cut  off,  and  it  is  always  the  diffuse 
light  from  the  sky  that  lights  up  the  shadows.  In  such  places  it 
will  be  found  difficult  to  combine  darkly  shaded  foliage  with 
sunlight  in  the  same  picture ;  this  result  can  only  be  obtained  by 
prolonged  exposure,  and  slow  and  careful  development ;  gene¬ 
rally  it  will  be  best  not  to  attempt  it,  if  it  can  be  avoided. 

The  development  must  always  be  graduated  not  merely  with 
respect  to  the  character  of  the  scene,  but  to  the  amount  of  ex¬ 
posure  that  has  been  given.  In  order  to  combine  exposure  and 
development,  and  so  to  get  the  best  possible  results  in  difficult 
cases,  the  following  observations  may  be  useful. 

A  view  that  is  strongly  illuminated  all  over,  with  few  con¬ 
trasts,  will  demand  a  moderately  short  exposure  and  a  long  de¬ 
velopment  with  a  weak  developer,  the  object  being  to  preserve 
detail,  and  yet  at  the  same  time  to  retain  contrast  enough  to  give 
life  to  the  whole. 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  215 

When  the  illumination  is  uniform  and  not  good,  or  where  all 
the  objects  are  non-actinic,  and  the  light  not  very  good,  we  shall 
want  a  very  prolonged  exposure  to  get  them  well  impressed. 
And  then  we  shall  need  a  long  development  with  a  weak  de¬ 
veloper,  otherwise  the  result  will  be  tame  and  flat. 

In  this  country  the  character  of  the  light  varies  between  ex 
tremely  wide  limits.  In  cloudy  weather  there  is  apt  to  be,  of 
course,  everywhere,  a  deficiency  of  contrast.  Such  light,  how¬ 
ever,  is  often  very  favorable  for  taking  near  foliage.  On  the 
other  hand,  when  the  sun  shines,  the  light  is  apt  to  be  very 
powerful,  and  as  the  air  with  us  in  clear  weather  is  apt  to  be  very 
transparent,  it  results  that  the  shadows  are  dark  and  wanting  in 
detail.  In  clear,  cloudless  weather  the  shadows  are  very  dark, 
and  in  such  weather  it  requires  great  experience  and  very  good 
management  to  get  first-rate  effects.  Attention  must  be  paid  to 
the  influence  both  of  the  season* and  of  the  time  of  day. 

Seasons. — The  landscape  begins  in  this  latitude  to  show  suffi¬ 
cient  foliage  to  commence  photographic  work  towards  the  first  of 
June,  though  the  forest  trees  are  not  well  in  leaf  till  a  fortnight 
later.  At  this  time  of  year  the  light  is  exceedingly  powerful, 
and  exposures  must  be  shortened. 

A  slight  excess  of  exposure,  generally  unimportant,  will  some¬ 
times  give  rise  to  solarization.  A  good  deal  of  care  and  circum¬ 
spection  will  be  required.  Sometimes,  when  the  sky  is  covered 
with  low  white  clouds  with  the  sun  just  breaking  through  them, 
the  power  of  the  light  is  truly  amazing. 

Throughout  the  spring  and  summer,  the  days  when  the  leaves 
are  still  are  far  from  frequent.  In  September,  and  even  towards 
the  end  of  August,  the  air  is  much  quieter,  and  it  is  far  less 
difficult  to  find  favorable  days  ;  the  light  is  also  softer.  On  the 
other  hand,  there  is  more  dust,  and  streams  are  apt  to  be  low,  so 
that  waterfalls  show  but  scanty  streams,  and  mill-dams,  often 
very  beautiful  at  other  times,  are  frequently  quite  dry. 

A  serious  trouble  at  all  seasons,  in  our  climate,  is  the  want  of 
softened  light.  We  have  but  a  few  of  those  partly  overcast  yet 
luminous  days  which  give  such  beautiful  effects  of  illumination 
and  such  soft  foliage ;  our  light  is  mostly  too  abundant  and 
piercing. 

Snow  Landscapes  should  receive  a  medium  exposure  and  a 
full  development,  for,  to  obtain  clean,  bright  snow  scenes,  all  the 


216 


PHOTOGEAPHIC  MANIPULATIONS. 


most  fully  lighted  snow  must  be  developed  to  absolute  opacity, 
shading  off',  however,  to  give  it  relief. 

Time  of  Day. — Two  or  three  hours  after  sunrise  the  light  is 
very  powerful  ;  it  goes  on  to  increase  till  about  11  o’clock,  then 
remains  stationary  till  12,  after  which  it  diminishes  till  sunset. 
The  afternoon  light  is  always  weaker  than  the  corresponding 
part  of  the  morning.  Thus,  the  light  two  hours  (for  example) 
before  sunset  is  not  half  as  powerful  as  two  hours  after  sunrise, 
though  the  sun  in  both  cases  is  equally  high.  This  is  said  to  be 
caused  by  the  greater  quantity  of  moisture  dissolved  in  the  air, 
though  the  explanation  is  doubtful. 

Cloudless  weather  is  always  unfavorable.  Clouds  act  as  re¬ 
flectors  to  light  up  the  shadows.  In  cloudless  weather  the  shadows 
are  always  very  dark,  and  are  apt  to  want  detail  in  the  image. 
In  such  weather,  the  middle  of  the  day  is,  in  the  writer’s  opinion, 
very  unsatisfactory  for  work.  In  the  early  morning,  and  in  the 
afternoon,  the  evil  of  want  of  clouds  is  less  felt.  At  these  times, 
also,  the  effects  of  scenery  are  more  agreeable,  the  shadows  are 
longer  and  give  more  relief,  the  air  is  generally  stiller.  Longer 
exposures  are  necessary,  of  course,  but  the  results  are  better.  In 
overcast  weather,  the  middle  of  the  day  is  apt  to  be  the  best 
time. 

Cast  Shadows  are  such  as  retain  more  or  less  of  the  form  of  the 
object  that  casts  them,  as  distinguished  from  the  more  indefinite 
shadow  that  comes  from  some  less  distinct  source.  Such  shadows 
are  often  the  source  of  exquisite  beauty  in  landscapes.  A  level 
foreground  of  grass  is  apt  to  be  flat  and  unmeaning ;  the  shadow 
of  a  tree  cast  across  it,  gives  it  at  once  life,  character,  relief.  The 
landscapist  cannot  pay  too  much  attention  to  such  effects  of  fore¬ 
ground. 

Generally,  the  more  that  shadow  is  diversified  the  finer  its 
effect.  A  large  dark  shadow  of  a  tree  is  far  less  beautiful  than 
one  in  which  the  sun  penetrates  the  leaves,  and  falls  in  irregular, 
broken  forms  upon  the  ground. 

When  it  is  required  that  a  house  shall  appear  in  the  foreground, 
a  diversified  shadow  upon  its  walls  has  an  extremely  good  effect. 
In  neither  case,  however,  must  the  lights  and  shadows  be  too 
much  broken,  or  the  effect  will  lack  breadth.  And  the  greatest 
care  must  be  taken  to  avoid  spottiness  of  effect.  As  this  is  a 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  217 

common  and  fatal  fault,  the  writer  will  endeavor  to  point  out  its 
source. 

Shadows  of  branches  and  boughs  through  which  the  sun  pene^ 
trates  partly,  and  which  retain  indistinctly  the  forms  of  leaves 
and  sprays,  are  very  beautiful.  A  level  sun  will  often  throw 
shadows  of  such  sprays  upon  the  trunks  of  trees,  with  an  exquisite 
effect.  So  shadows  of  leaves  and  boughs  on  walls,  houses,  roads, 
and  grass,  are  often  very  beautiful.  But  it  is  an  essential  con¬ 
dition  that  the  shadows  must  he  transparent ,  and  shall  present  only 
a  moderate  degree  of  contrast  with  the  lights.  If,  however,  we  place 
the  camera  in  a  grove  and  take  a  picture,  we  shall  probably  get 
black  shadows  on  the  ground,  interspersed  with  white  patches  of 
sunlight,  and  these  effects,  instead  of  being  of  a  wholly  subordi¬ 
nate  character,  will  strike  the  eye  before  anything  else  in  the 
view.  Such  an  effect  is  indescribably  bad,  and  to  be  avoided 
with  the  utmost  care. 

Parallel  patches  of  shadow  are  especially  ugly.  These  are  apt 
to  occur  when  trees  present  themselves  in  rows,  with  sunshine 
penetrating  between  each  two  trees. 

The  tree,  the  great  beauty  of  the  landscape,  offers  peculiar 
difficulties  in  photography,  owing  to  the  non-actinic  color  of  its 
leaves.  For  this  reason  it  has  been  thought  advisable  to  use 
much  bromide  in  collodion  intended  for  landscape  photography; 
the  true  explanation  of  its  utility  has  been  already  given.  There 
is  a  remarkable  difference  between  leaves  of  different  trees,  which 
it  will  be  necessary  to  bear  in  mind.  Some  have  a  brilliant  sur¬ 
face,  as  if  they  had  been  varnished;  such  are  the  sour-gum,  black- 
oak,  and  others.  From  this  we  descend  through  every  degree  to 
those  leaves  which  scarcely  return  any  light,  such  as  the  white- 
oak,  &c.  The  first  sort,  if  in  direct  sunshine,  are  apt  to  produce 
a  particularly  disagreeable  effect;  they  send  back  so  much  light, 
that  they  develop  to  full  opacity  by  the  time  the  rest  of  the 
picture  has  come  up  to  printing  strength,  and  so  print  quite 
white.  This  is  unnatural  and  unpleasing,  and,  as  far  as  pos¬ 
sible,  to  be  avoided.  In  cloudy  weather  such  leaves  photograph 
exceedingly  well.  Ivy-leaves  on  buildings  easily  give  a  very 
beautiful  effect.  They  send  back  a  good  amount  of  light  and  not 
too  much,  and,  as  they  are  apt  to  look  all  in  the  same  direction, 
each  leaf  is  bordered  by  a  shadow.  Thus  each  leaf  is  well  made 
out,  and  the  effect  is  particularly  pleasing  and  exceedingly  easy 
to  catch,  more  so,  perhaps,  than  with  any  other  sort  of  foliage. 
15 


218 


PHOTOGRAPHIC  MANIPULATIONS. 


It  has  been  often  advised  in  photography  to  have  the  sun  well 
behind  the  camera.  This,  however,  is  a  rule  of  very  doubtful 
validity.  When  the  sun  shines  full  upon  a  group  of  trees  in  the 
middle  distance,  the  forms  of  the  individual  trees  are  never  well 
made  out,  and  the  result  is  apt  to  be  a  mere  mass  of  brilliantly 
lighted  foliage.  Often  the  separate  twigs  and  boughs  may  stand 
out  in  consequence  of  dark  shadows  falling  between  the  leaves, 
but  the  beautiful  rounded  effect  of  each  particular  tree  is  only 
well  thrown  out  by  a  good  side-light.  This  inferiority  of  effect 
produced  by  having  the  sun  directly  or  nearly  behind  the  camera, 
on  trees  in  the  middle  distance,  is  very  striking.  Near  foliage , 
however,  bears  having  the  sun  behind  the  camera  perfectly  well. 
But  the  exquisite  beauty  of  the  rounded  forms  of  individual  trees 
in  the  middle  distance  is  only  well  rendered  by  a  side-light. 

One  reason  why  this  light  from  behind  has  been  extensively 
used  is  that  it  is  the  least  exposed  to  blurring .  Whenever  dark 
masses  stand  out  against  a  bright  sky,  the  light  has  a  tendency 
to  get  round  and  intrude  upon  the  shadow ;  an  effect  that  arises 
from  reflection  from  the  back  surface  of  the  glass.  The  partial 
opacity  of  the  film  scatters  the  light  that  passes  through  it  in 
every  direction,  so  that  portions  reach  the  back  at  very  oblique 
angles,  and  may  return  to  the  face  at  considerable  distances 
from  where  they  entered.  To  a  large  extent  this  may  be  avoided 
by  wet  red  blotting-paper  on  the  backs  of  wet  plates  and  glycerine 
plates  (a  precaution  which  should  never  be  neglected),  and  by 
painting  the  backs  of  dry  plates. 

Near  foliage  should  be  represented  invariably  in  half-tone,  and 
this  eifect  is  generally  obtained  more  easily  when  the  sun  is  not 
too  bright,  especially  in  the  case  of  the  polished  leaves  already 
spoken  of.  Distant  foliage  is  far  more  easy  to  manage,  and  bears 
the  brightest  sunshine  perfectly.  It  is  far  better  rendered  when 
the  sun  falls  upon  it  from  the  side  than  when  the  sun  is  either 
nearly  before  or  nearly  behind  the  spectator.  A  fine  single  tree 
or  grove  of  trees  lighted  from  the  side  affords  a  beautiful  play  of 
light  and  shade,  which  disappears  when  the  sun  is  in  the  line  of 
view  before  or  behind,  or  even  approaches  to  that  direction. 

Natural  clouds  are  a  great  beauty  when  they  can  be  included 
in  a  landscape.  The  difficulties  here  are  twofold.  It  is  not  very 
common  (at  least  in  our  climate)  that  there  are  clouds  such  as  it 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  219 


is  desirable  to  take.  In  our  fine  weather  we  have  mostly  a  clear 
or  nearly  clear  sky.  And  when  there  are  beautiful  clouds,  the 
weather  is  apt  to  be  too  windy  for  photographic  work.  But  the 
greatest  difficulty  lies  in  the  fact  of  the  great  luminosity  of  clouds. 
When  the  sun  is  shining,  the  darkest  part  of  a  cloud  is  generally 
more  luminous  than  the  whitest  object  in  a  landscape.  The  eye 
scarcely  realizes  this  in  observing  a  landscape,  but  it  is  easily 
recognized  on  the  ground  glass.  The  consequence  is  that  although 
the  clouds  appear  in  the  commencement  of  development,  yet  they 
are  buried  in  a  mass  of  deposit  before  the  details  of  the  landscape 
are  got. 

There  are  several  methods  of  obviating  this  to  some  extent, 
though  it  must  be  confessed  that  they  leave  much  to  be  desired. 

The  camera  may  be  provided  with  a  sky-shade ,  a  shutter  in 
front  of  the  lens  (Figs.  92  and  94),  which  may  be  slowly  raised 
during  exposure,  so  as  to  diminish  the  light  admitted  from  the  sky. 

Or  the  hand,  the  hat,  or  the  shutter  of  the  plate  holder  may  be 
used  in  the  absence  of  a  sky-shade. 

In  either  of  these  cases  a  trial  should  be  made  of  the  move¬ 
ments  beforehand,  and  the  effect  watched  upon  the  ground  glass, 
that  the  operator  may  see  in  what  position  of  the  shading  object 
the  sky  begins  to  be  uncovered. 

The  inclined  diaphragm  (Fig.  40,  p.  66),  by  reducing  the  light 
from  the  sky,  will  aid  in  obtaining  clouds. 

To  secure  clouds,  the  opportunity  also  should  be  favorable. 
The  landscape  should  be  wide  and  well  lighted,  in  order  that  a 
brief  exposure  may  suffice  for  the  terrestrial  objects. 

According  to  Mr.  H.  T.  Anthony,  a  developer  of  double  sul¬ 
phate  of  iron  and  ammonia  30  grains  to  the  ounce,  sulphate  of 
copper  5  grains,  and  acetic  acid  as  needed,  is  very  favorable  to 
the  obtaining  of  clouds. 

An  agreeable  diversification  of  the  foreground  is  a  capital 
point  in  a  landscape.  It  has  been  already  remarked  how  much 
this  is  aided  by  shadows.  Almost  any  characteristic  and  promi¬ 
nent  objects  will  have  a  good  effect;  logs,  stones,  and,  still  more, 
rocks,  bushes — anything  that  breaks  the  level  and  changes  the 
lines,  also  attracts  and  pleases  the  eye,  not  in  itself,  but  in  the 
general  character  that  it  imparts.  It  may  generally  be  affirmed 
that  scarcely  anything  can  so  much  detract  from  the  effect  of  a 
landscape  as  an  unbroken  foreground,  level  in  form,  and  uniform 


220 


PHOTOGRAPHIC  MANIPULATION'S. 


in  light.  Such  a  foreground  will  mar,  if  not  destroy,  the  effect  of 
the  finest  objects.  The  artistic  photographer  will  always  change 
his  position  to  avoid  such  a  foreground;  or,  if  he  is  tied  down  to 
a  particular  spot  from  some  imperative  cause,  he  will,  if  possible, 
have  some  object,  such  as  a  log,  a  large  stone,  or  a  trunk  of  a 
tree,  thrown  where  it  will  support  his  lines,  as  explained  more 
fully  beyond.  High  banks  are  very  picturesque  objects,  and 
often  aid  to  make  beautiful  foregrounds. 

Bringing  Out  the  Foreground.  Acceleration  of  Exposure. — Often 
the  foreground,  especially  if  consisting,  as  it  so  commonly  does, 
chiefly  of  foliage,  lags  behind  in  development ;  and  when  some 
other  parts  of  the  picture  have  reached  a  full  intensity,  so  that 
the  development  must  perforce  be  stopped,  the  foreground  will 
often  be  still  thin  and  poor.  This  is  a  great  injury  to  a  picture, 
which  is  helped  by  nothing  more  than  by  a  properly  exposed 
and  developed  foreground. 

The  writer  has  succeeded  in  obviating  this  difficulty  to  a  con¬ 
siderable  extent  as  follows:  He  takes  a  piece  of  white  pasteboard, 
shaped  as  in  Fig.  107,  and  of  such  a  size  that 
whilst  the  top  lies  flat  against  the  inside  top 
of  the  camera,  the  tapering  sides  rest  upon 
the  bottom,  and  act  like  legs  to  support  the 
top  in  its  place.  The  inside  is  colored  rose- 
red  with  carmine  (lump  carmine,  a  grain  or 
two  dissolved  in  half  an  ounce  of  water, 
with  a  drop  or  two  of  liquid  ammonia,  is  better  than  the  paint). 
The  red  light  diffused  and  reflected  by  the  surface  of  this  paper 
considerably  increases  the  force  of  the  adjoining  portions  of  the 
image,  without  in  the  least  tending  to  produce  fog.  The  sides 
should  taper  very  much,  as- it  is  not  desirable  that  any  part  of 
the  red  paper  should  be  alongside  of  any  part  of  the  sky. 

There  is  in  this  device  a  real  and  solid  utility,  and  the  writer 
never  now  goes  out  to  take  views  without  this  adjunct.  A  piece 
of  pasteboard  blackened  with  ink,  and  of  such  a  size  as  to  fit 
against  one  of  the  sides  of  the  camera,  and  so  cover  one  of  the 
legs  of  the  red  pasteboard  in  case  there  is  much  sky  on  that  side, 
is  convenient  to  have. 


Fig.  107. 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  221 


3. — Materials. 


Fig.  108. 


Camera. — The  most  convenient  form  of  camera  for  ordinary 
use  is  that  represented  in  Fig.  94,  p.  149,  except  that,  especially 
if  the  camera  be  large,  the  writer  prefers  the  wooden  brace  shown 
in  Fig.  92.  When  it  is  intended  to  pack  the  camera,  to  carry  to  a 
distance,  it  is  convenient  to  have  the  bottom  jointed  and  hinged, 
though,  this  system  weakens  the  whole  construction. 

Slides. — If  the  dry  process  is  worked,  the  photographer  can 
use  Changing  Boxes ,  contrived  to  carry  a  number  of  plates,  and 
transfer  them,  one  by  one,  to  a  peculiarly  made  slide ;  or  he  can 
use  separate  slides,  which  may  be  made  to  carry  two  plates  each, 
and  are  then  called  Double  Bachs.  This  is  the  plan  preferred  by 
the  writer. 

Tripods. — A  light  folding  tripod  is  essential  for  field  work;  and 
as  much  of  the  photographer’s  comfort  will  depend  upon  having 
a  good  tripod,  the  writer  has 
made  drawings  of  the  parts  of 
the  form  which  he  prefers. 

Fig.  108  shows  the  top  table. 

It  is  made  of  three  thin  pieces 
of  wood  glued  firmly  together, 
and  having  the  form  of  a  round¬ 
ed  triangle.  At  each  corner  a 
block  is  fastened  underneath, 
carrying  stout  pins,  A,  B ,  which 
slip  into  holes  in  the  legs,  the 
tops  of  which  are  shown  in  the 
figure. 

At  the  centre  is  a  circular  opening  in  the  top  thickness,  in  the 
middle  of  which  circle  is  set  the  screw  S.  There  is  no  screw- 
thread  in  the  table,  the  screw  merely  passes  through  it  and  screws 
into  the  camera.  A  pin  passed  through  the  stem  of  the  screw, 
just  above  where  it  passes  through  the  table,  prevents  it  from 
dropping  out;  this  is  a  great  convenience,  often  neglected  by  the 
makers,  thus  subjecting  the  photographer  to  the  chance  of  over¬ 
looking  the  screw  in  going  out,  and  so  losing  his  day. 

The  legs,  one  of  which  is  shown  in  Fig.  109,  fold  over  in  the 
middle,  to  save  room.  The  cross-piece  near  the  upper  end  moves 
on  a  hinge,  and  permits  of  shutting  the  whole  up  flat.  In  Fig. 
110  the  writer  has  drawn  the  joint  on  a  larger  scale.  When  the 


222 


PHOTOGRAPHIC  MANIPULATION'S. 


leg  is  straightened  out,  a  small  brass  cross-piece,  attached  by  two 
screws,  confines  the  lower  piece  in  its  position,  and  a  strong  thumb- 


Pig.  109.  Fig.  110. 


screw  at  the  side,  when  tightly  turned,  makes  the  whole  perfectly 
rigid.  It  is  surprising  how  light  a  tripod,  thus  made,  will  hold 
a  heavy  camera  quite  steady. 

For  additional  information  on  materials,  see  Chapter  XV. 

§  4. — Manipulations  in  the  Field. 

If  the  wet  process  is  the  one  selected,  the  photographer  will 
either  use  a  developing  box ,  a  tent ,  or  a  dark  room  on  wheels.  One 
of  the  simplest  tent  contrivances  is  a  thick  black  cloth  stretched 
over  the  camera  tripod,  and  kept  in  place  by  stones.  In  the  de¬ 
veloping  box,  the  hands  and  arms  only  are  inserted  into  sleeves, 
whilst  the  operations  are  watched  through  yellow  glass. 

All  the  troubles,  and  there  are  many,  that  accompany  these 
methods  of  operating,  are  avoided  by  the  use  of  dry  plates.  And 
it  is  certain  that  the  most  improved  methods  of  dry  plate  work 
give  results  fully  equal  to  those  of  the  wet  process. 

Whichever  method  be  adopted,  an  observance  of  the  following 
rules  will  save  a  great  deal  of  vexation  and  the  loss  of  many 
negatives,  occasionally  perhaps  of  a  whole  day’s  work. 

At  the  commencement  of  a  day’s  work,  see,  once  for  all — 

1.  That  the  camera  is  light-tight,  and  that  there  are  no  cracks 
in  the  front  or  holes  in  the  bellows  body.  Cap  the  lens,  cover  in 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  223 


the  head  well,  and  look  into  the  camera  with  the  ground  glass  let 
down,  racking  back  pretty  well,  to  open  the  folds  of  the  bellows. 

2.  See  that  the  lens 

Is  free  from  dust. 

Has  no  dew  on  it. 

That  the  parts  of  the  lens  and  of  the  mount  are  properly 
put  together. 

For  each  exposure  make  sure. 

3.  That  the  camera  and  tripod  are  perfectly  steady. 

4.  Invariably  use  the  largest  aperture  to  compose  the  picture. 
Make  sure  that  no  near  objects  out  of  focus  are  showing  in  the 
foreground,  which  may  easily  happen  with  shrubs,  weeds,  and 
the  like.  Also  that  no  overhanging  foliage  is  intruding  upon 
the  upper  corners  of  the  plate,  to  appear,  to  the  dismay  of  the 
photographer,  when  he  develops,  as  large,  formless  objects,  ruin¬ 
ing  probably  his  picture. 

5.  Adjust  the  swing-back.  Kemember  that  if  the  screws  which 
fasten  it  are  not  turned  perfectly  tight,  they  will  probably  move 
when  the  plate  holder  is  pressed  up  to  attach  it. 

6.  If  working  with  dry  plates,  make  perfectly  sure  that  you 
are  not  exposing  a  plate  that  has  been  already  exposed  before. 
If  habitually  using  dark  slides  or  double  backs,  have  each 
painted  conspicuously  with  a  number  on  the  shutter,  and  expose 
in  regular  rotation.  If  using  a  changing  box,  adopt  a  regular 
system  of  changing  the  plate  immediately  after,  or  immediately 
before,  exposing ;  always  the  same. 

7.  If  the  sliding  front  has  been  moved  up  or  down  or  side¬ 
ways,  for  a  previous  exposure,  make  sure  that  it  has  been  re¬ 
placed.  If  the  camera  has  been  carried  a  distance,  the  front 
may  have  jolted  down,  and  if  not  attended  to,  some  of  the  cor¬ 
ners  may  be  defective  in  the  image. 

8.  After  arranging  and  composing  the  picture  with  the  largest 
stop  (in  order  that  you  may  see  exactly  what  the  picture  will  be 
like),  turn  the  screw  of  the  tripod  under  the  camera ,  hard ,  so  that 
there  shall  not  be  the  slightest  change  of  position  during  the 
subsequent  manipulations. 

9.  How  put  in  the  diaphragm  which  you  intend  to  use,  and 
focus  with  it  (never  with  the  large  one  by  which  the  picture  was 
composed,  and  for  two  reasons :  1st.  It  will  not  give  a  good 
focus,  being  too  large.  2d.  If  it  did,  its  focus  would  not  be  the 
same ,  the  smaller  the  stop  the  longer  the  focus). 


224 


PHOTOGRAPHIC  MANIPULATIONS. 


The  loose  diaphragms  that  slide  into  slits  in  the  tube  (Water- 
house  diaphragms)  are  apt  to  drop  out.  To  avoid  this,  bend  the 
shank  a  little. 

10.  Uncap  the  lens  gently,  pausing  at  the  moment,  to  insure 
perfect  rest. 

11.  Watch  the  foliage  intently  during  exposure,  and  at  the 
slightest  sign  of  movement,  replace  the  cap  until  the  movement 
wholly  subsides,  and  repeat  this  as  often  as  necessary — a  dozen 
times  if  needful. 

The  same  objects  will  appear  so  differently  in  different  lights, 
that  the  painstaking  photographer  will  not  hesitate  to  wait  or 
to  return  when  he  finds  the  illumination  to  be  unsuitable  for  his 
purposes.  There  is  a  story  told  of  a  distinguished  landscapist 
that  he  once  waited  three  weeks  to  get  good  weather  and  a  par¬ 
ticular  effect  of  light  upon  a  scene  that  he  had  come  to  photo¬ 
graph.  There  is  some  contrast  between  this  and  the  rapid  worker 
who  points  his  camera  at  everything  that  catches  his  eye,  and 
exposes  his  dozen  of  dry  plates  in  an  hour  or  two.  It  should  be 
laid  down  as  an  axiom  by  every  worker,  that  a  good  negative  is 
very  valuable,  a  tolerable  negative  worth  absolutely  nothing.  It 
is  at  least  as  troublesome  to  print  a  tolerable  negative  as  a  good 
one,  and  the  prints  from  the  tolerable  one  are  not  worth  the  pains 
they  have  cost  in  printing.  Twenty  copies  from  a  good  negative 
are  valuable  for  exchanging  against  prints  from  good  negatives 
belonging  to  others;  but  twenty  prints,  each  from  a  tolerable  and 
different  negative,  are  nearly  worthless.  ISTo  multiplication  of 
indifferent  results  will  give  good  ones,  and  the  experimenter  will 
derive  more  satisfaction  from  a  single  thoroughly  good  negative 
than  from  a  score  or  a  hundred  of  indifferent  or  tolerable  ones. 
Good  results  will  come  only  with  care,  thought,  close  observa¬ 
tion,  and  a  resolution  to  have  things  right  at  any  cost  of  time 
and  trouble.  Care-taking  soon  becomes  a  matter  of  course,  and 
the  habit  once  acquired,  is  invaluable. 

Adapting  Flanges . — The  inconvenience  arising  from  flanges  of 
different  sizes  has  been  already  pointed  out  (p.  96).  The  writer 
finds  this  annoyance  materially  lessened  by  having  adapting 
flanges  made  for  lenses,  so  that  several  lenses  may  screw  into 
one  and  the  same  flange.  Such  adapters  can  readily  be  made 
by  any  optician  at  a  trifling  cost. 

Focussing. — A  black  cloth  which  will  perfectly  exclude  the 


LANDSCAPE  AND  ARCHITECTUR  A  L  PHOTOGRAPHY.  225 

light  is  essential.  Black  waterproof  is  suitable,  and  a  piece  a 
yard  and  a  half  square  will  be  a  convenient  size. 

Photographers  differ  very  much  in  their  ideas  of  how  a  focus 
should  be  taken.  In  the  first  edition  of  this  manual  it  was 
recommended  to  focus  at  a  point  in  the  foreground  half-way 
between  the  centre  and  a  corner,  racking  back  as  far  as  prac¬ 
ticable,  and  then  putting  on  a  small  enough  stop  to  obtain  the 
definition  needed. 

ISTow,  however,  the  writer  has  gradually  adopted  the  following 
plan :  There  will  be  with  any  lens  a  stop  which  one  habitually 
uses  when  the  objects  are  not  very  different  in  their  distances 
from  the  camera,  and  another,  the  next  smaller,  used  when  the 
differences  are  greater.  Therefore,  selecting  for  the  view  about 
to  be  taken  the  stop  deemed  appropriate,  proceed  to  focus  on  the 
distance,  and  then  rack  back  the  focussing  screen  just  as  long  as 
the  distance  will  bear  it,  without  its  definition  suffering  too  much. 
This  ought  to  bring  the  foreground  into  focus ;  if  it  does  not,  a 
smaller  stop  must  be  substituted,  or  else  the  position  changed  so 
as  to  exclude  the  near  objects  that  cannot  be  got  into  focus  along 
with  the  distance. 

Either  of  these  alternatives  is  unsatisfactory,  because  it  may 
be  very  desirable  to  include  that  particular  part  of  the  fore¬ 
ground,  and  a  small  stop  is  always  bad. 

But  if  the  camera  have  the  valuable  aid  of  the  swing-back,  the 
question  is  greatly  simplified.  The  photographer  will  be  enabled 
to  get  an  equally  good  general  focus  with  a  larger  stop,  and  con¬ 
sequently  with  better  detail  in  the  shadows,  and  better  spacing 
out  of  the  distances.  A  swing-back  should  always  be  double, 
that  is,  have  both  a  horizontal  and  a  vertical  motion. 

,The  vertical  'pivot  is  to  be  used  when,  as  so  often  happens,  the 
objects  at  one  side  of  the  view  are  nearer  than  those  on  the  other. 
The  side  on  which  the  nearer  objects  fall  is  drawn  a  little  away 
from  the  lens. 

The  horizontal  pivot  is  useful  in  getting  the  foreground  into 
focus  at  the  same  time  with  the  distance.  To  this  end,  focus  on 
the  distance,  rack  out  the  focussing  screen  as  long  as  the  distance 
will  bear  it.  Then  draw  the  top  of  the  screen  away  from  the 
lens,  until  the  foreground  is  perfect.  Both  this  and  the  vertical 
action  may  be  combined  (see  also  p.  148). 

The  usefulness  and  convenience  of  the  swing-back  for  bringing 
the  foreground  into  focus  is  exceedingly  great,  and  when  once 


226 


PHOTOGRAPHIC  MANIPULATIONS. 


used  habitually,  this  contrivance  is  felt  to  be  indispensable. 
There  is  one  case,  however,  in  which  particular  caution  is  needed 
in  its  application. 

If  both  the  upper  corners  of  the  picture  be  occupied  by  near 
foliage,  then  any  drawing  out  of  the  upper  side  of  the  swing- 
back  to  regulate  the  foreground  will  be  apt  to  throw  the  corner 
foliage  out  of  focus,  and  deform  it.  In  such  cases  it  will  be 
needful  to  move  the  tripod  farther  back  in  order  to  lessen  the 
difficulties  of  the  position. 

If  one  upper  corner  only  be  covered  by  foliage,  and  if  the 
extreme  distance  of  the  view  lie  towards  the  other  end,  we  may 
then  draw  out  the  foreground  without  danger,  because  the  foliage 
in  the  upper  corner  can  be  got  into  focus  again  by  regulating 
the  vertical  pivot,  and  thus  at  the  same  time  the  distance  at  the 
farther  side  will  be  also  harmonized  in  focus. 

Some  persons  are  as  anxious  for  sharpness  in  the  distance  as 
in  the  foreground,  and  will  exhibit  a  print  with  the  boast  that 
the  extreme  distance  will  bear  a  microscope.  As  the  eye  cannot 
see  natural  objects  in  this  fashion,  it  can  scarcely  be  right  to 
depict  them  so.  And  when  we  examine  the  works  of  the  great 
masters  of  landscape  painting,  we  find  that,  with  the  power  to 
draw  their  distances  precisely  as  they  pleased,  they  did  not  think 
right  to  make  them  sharply  cut. 

We  find  that,  as  distance  softens  down  outlines  to  the  eye,  so 
when  outlines  are  softened  down,  the  eye  infers  distance. 

Not  that  this  principle  is  to  be  carried  to  excess,  and  made  an 
excuse  for  blundering  work.  It  is  only  that  the  same  sharpness 
is  not  to  be  exacted  in  the  distance  as  in  the  foreground ;  espe¬ 
cially  as  this  can  only  be  attained  by  the  use  of  a  very  small 
stop,  which  greatly  mars  the  boldness  and  life  of  the  image. 

§  5.— The  Wind. 

In  all  landscapes  the  chief  beauty  lies  in  the  foliage,  and  it  is 
necessary  that  this  should  be  absolutely  still,  to  be  satisfactorily 
represented.  Every  one  who  attempts  landscape  photography 
has  had  severe  experience  of  this  sort,  and  fully  understands  the 
ruinous  effect  produced  upon  a  picture  by  blurred  masses  of 
leaves. 

It  would  be  difficult  to  exaggerate  the  annoyance  caused  to  the 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  227 


photographer  by  this  unending  source  of  trouble.  It  is  impos¬ 
sible  to  foretell  what  the  prospect  of  wind  is,  therefore  a  long 
excursion  may  be  taken  uselessly,  or  may  be  abandoned  only  to 
see,  when  too  late,  the  wind  entirely  subside. 

The  following  represents  what  aid  can  be  given  in  this  direc¬ 
tion  : — 

Time  of  Day. — The  very  early  morning  is  apt  to  be  calm,  and, 
still  more  so,  the  afternoon  for  an  hour  or  two  before  sunset. 
Both  of  these  are  excellent  times  for  photographic  work.  The 
exposures  in  the  late  afternoon  are  necessarily  prolonged,  but  the 
quietness  of  the  air  generally  makes  this  easy. 

Between  eight  and  ten  o’clock  A.  M.  the  wind  is  apt  to  rise, 
sometimes  earlier,  sometimes  later.  It  may  subside  towards 
midday,  but  quite  as  often  not.  Gradually  towards  three  or  four 
o’clock  in  autumn,  four  or  five  in  spring  and  summer,  a  sub¬ 
sidence  may  be  hoped  for,  and  then  no  time  should  be  lost  in 
improving  it.  It  is  one  advantage  of  dry  plates  that  they  can 
follow  each  other  without  losing  valuable  time  in  sensitizing  and 
developing ;  the  collodio-bromide  dry  plates  hereafter  to  be  de¬ 
scribed  are,  by  reason  of  their  sensitiveness,  excellent  for  after¬ 
noon  exposures. 

Seasons. — The  spring  with  us  is  apt  to  be  windy,  with,  how¬ 
ever,  occasional  calm  days,  which  become  rather  more  numerous 
in  June  and  July.  August  and  September  have  mostly  more 
quiet  days  than  any  other  months.  October  has  beautiful  quiet 
days  occasionally,  with  fine,  soft  illumination.  By  the  first  of 
November  the  foliage  is  pretty  well  gone.  Then,  in  place  of  the 
soft  lights  and  shadows  of  the  woods,  we  get  masses  of  parallel, 
gray  trunks,  which  produce  the  very  worst  effects.  A  single 
tree,  especially  an  oak  tree,  devoid  of  leaves,  is  a  beautiful  object, 
its  branches  give  gracefully  opposing  lines,  that  support  each 
other ;  but  there  is  nothing  of  this  sort  in  a  wood. 

When  the  wind  blows  steadily  it  is  a  mere  waste  of  time  and 
material  to  go  out  to  photograph,  however  tempting  the  light 
may  be;  except,  indeed,  we  go  expecting  only  to  make  use  of 
the  late  afternoon.  On  not  very  windy  days  we  are  almost  sure 
to  have  an  hour  or  two  of  calm  before  sunset. 

Often  the  wind  blows  in  puffs.  In  this  case  we  closely  watch 
the  foliage  and  re-cap  the  lens  the  instant  the  first  movement 
shows  itself.  With  care,  quickness,  and  gentleness,  it  is  wonder¬ 
ful  how  much  may  be  accomplished  in  this  way.  It  should  be 


228 


PHOTOGRAPHIC  MANIPULATIONS. 


remembered,  however,  that  if  the  puffs  of  wind  between  tbe  quiet 
times  are  violent,  it  does  not  follow  that  tbe  leaves,  after  this 
violent  agitation,  will  settle  down,  each  leaf  to  the  exact  previous 
position. 

For  the  most  part,  however,  it  is  a  waste  of  time  to  attempt  to 
photograph  landscapes  in  windy  weather.  The  evil  effects  of 
very  slight  winds  may  be  materially  diminished  by  observing 
one  or  two  precautions. 

When  light  branches  are  projected  against  a  bright  sky  or 
clouds,  the  least  motion  of  the  leaves  allows  the  bright  light  of 
the  sky  to  pass  in  behind  them.  The  result  is  that  the  leaves 
appear  shrunk  away  and  blurred,1  an  effect  very  often  seen  and 
most  displeasing.  If  the  sky  is  very  dense,  and  prints  perfectly 
white,  such  branches  should  always  be  painted  out.  A  similar 
result  follows  when  branches  are  projected  against  the  reflection 
of  the  sky  on  water,  or  against  any  other  bright  object. 

Again,  where  boughs  with  glossy  foliage,  well  illuminated, 
stand  out  against  deep  shadow,  and  are  moved  by  wind,  they 
carry  their  bright  reflection  with  them,  and  their  image  is  ex¬ 
tended,  in  place  of  being  shrunk  away  as  in  the  previous  case. 
Each  leaf,  instead  of  being  small  and  sharp  cut,  as  we  would  wish 
to  have  it,  is  large,  blurred,  and  undefined. 

Therefore,  if  the  air  be  somewhat  in  motion,  the  landscapist 
will  do  well  to  avoid  foliage  in  either  of  these  two  positions, 
which  are  those  that  produce  the  worst  effects.  For  when  foliage 
standing  before  other  foliage,  and  nearly  equally  illuminated,  is 
moved,  the  result,  though  anything  but  pleasing,  is  not  so  very 
injurious  as  in  the  other  cases. 

On  those  priceless  days,  when  the  light  is  neither  too  strong 
nor  too  weak,  and  the  foliage  perfectly  still,  the  photographer 
will  do  well  to  turn  his  attention  especially  to  those  landscapes 
in  which  the  chief  beauty  lies  in  the  foreground.  Foliage  should 
be  introduced  quite  near  to  the  camera,  provided  it  can  be  kept 
in  good  focus  together  with  more  distant  objects.  Projecting 
boughs  seen  against  the  reflection  of  sky  in  water,  so  objection¬ 
able  in  the  former  case,  may  now  be  made  to  produce  the  most 
charming  results,  especially  when  accompanied  by  their  reflected 
images. 

1  When  no  paper  is  placed  behind  the  plate  (or  color  on  the  back  of  dry 
plates),  the  same  result  may  be  expected  by  reflection  from  the  back  of  the 
plate,  quite  independently  of  any  movement  of  the  leaves. 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  229 

When  it  is  intended  to  photograph  immovable  objects  in  a 
heavy  gale,  it  is  very  desirable  to  find,  if  possible,  some  suitable 
support,  such  as  a  wall,  a  rock,  or  the  stump  of  a  tree,  on  which 
to  place  the  camera,  which  is  then  steadied  by  placing  on  it  a 
heavy  stone.  Perfect  steadiness  may  in  this  way  be  obtained. 
In  the  absence  of  these  resources,  a  cord  may  be  fastened  to  the 
screw  under  the  table  of  the  tripod,  and  a  heavy  stone  be  tied  to 
the  other  end,  and  let  to  hang  down.  Or  it  has  been  proposed 
to  tie  a  loop  in  the  cord,  reaching  just  short  of  the  ground,  and 
to  put  the  foot  into  the  loop,  and  thus  hold  steady  the  camera. 

It  remains  to  say  a  word  respecting  the  wind,  in  its  relation  to 
long  and  short  exposures. 

It  has  been  said  that  the  wind  does  not  act  more  injuriously 
upon  a  long  exposure  than  upon  a  short  one,  the  effect  having  the 
same  average  in  each  case,  in  proportion  to  the  exposure.  This 
view  is,  I  am  persuaded,  erroneous.  The  wind  rarely  blows 
steadily  (such  weather  is  to  be  particularly  avoided),  but  gene¬ 
rally  in  puffs.  And  these  puffs  are  apt  to  come  at  intervals,  such 
that,  by  watching,  a  short  exposure  can  be  caught  between  them, 
when  a  long  one  cannot  possibly. 

Indications  of  Weather. — As  the  photographer’s  success  in  out¬ 
door  work  is  always  dependent  upon  the  weather,  all  means  of 
judging  beforehand  of  what  weather  may  be  expected,  acquire 
no  small  importance.  These  signs  differ  materially  in  different 
countries  ;  thus  the  writer,  after  a  careful  observation  of  the  indi¬ 
cations  furnished  by  the  English  Admiralty  for  the  guidance  of 
shipmasters,  believes  that,  here  at  least,  they  are  quite  unreliable. 
The  following  are  what,  from  long  experience  and  personal  ob¬ 
servation,  have  appeared  to  him  useful. 

And,  first,  as  to  wind.  The  direction  of  the  wind  has  much  to 
do  with  its  probable  force.  A  westerly  Wind  may  be  expected 
to  blow  moderately;  a  northwesterly  wind  strongly,  and  often  vio¬ 
lently;  a  north  and  northeast  wind  strongly;  an  east  wind  (if  not 
inclining  northwards)  is  in  clear  summer  weather  not  often  strong. 
But  it  is  from  southeasterly  and  southerly  winds  that  the  best  pho¬ 
tographic  weather  is  apt  to  come,  provided  they  do  not  bring  rain. 
Often  with  them  the  air  is  perfectly  calm.  When  the  direction 
gets  round  to  southwest,  we  have  light  breezes,  often  in  puffs,  a 
state  of  weather  very  favorable.  Thus  we  are  most  apt  to  have  good 
photographic  opportunities  with  a  southwesterly  wind,  but  the 


230 


PHOTOGRAPHIC  MANIPULATIONS. 


best  weather  we  have  comes  with  a  southeast  or  southerly  wind, 
though  such  a  wind  is  less  sure  to  bring  it. 

The  clouds  give  many  useful  indications.  Thus,  if  in  the  early 
morning  we  see  the  clouds  moving  rapidly,  then,  although  the 
air  below  may  be  quite  still,  we  are  almost  sure  to  have  it  rise  in 
an  hour  or  two,  and  blast  the  fairest  expectations.  Much  may 
be  inferred  from  the  forms  of  clouds.  Feathery  clouds  almost 
always  bring  wind ;  mottled,  irregular  clouds  like  flocks  of  sheep 
may  or  may  not.  The  most  favorable  indication  for  calm  air  is 
when  the  clouds  form  in  long,  smooth,  thin  forms,  imperceptibly 
blending  into  each  other  and  into  the  sky;  this  appearance  gene¬ 
rally  portends  a  still  air  and  a  soft  light.  Abrupt  contrasts  in 
clouds  are  more  likely  to  bring  wind. 

The  previous  condition  of  the  weather  often  affords  a  means  of 
judging.  The  first  day  after  a  storm  is  apt  to  be  windy,  each 
succeeding  day  is  more  likely  to  be  calm,  and  the  calmest  weather 
is  apt  to  be  that  which  comes  immediately  before  the  next  storm. 

The  above  indications  relate  to  stillness .  As  to  clearness ,  the 
following  will  be  found  useful : — 

A  mackerel-back  sky  indicates  a  change  of  weather.  This  name 
is  given  to  collections  of  little  clouds,  three,  four,  or  more  times 
as  long  as  they  are  wide,  and  arranged  in  parallel  groups.  This 
indication  rarely  fails  to  be  followed  by  bad  weather  within 
twenty-four  hours. 

A  red  sunset  generally  precedes  a  fine  day,  a  gray  sunset  a  rainy, 
or,  at  least,  an  overcast  day. 

Although  it  is  said  that  with  the  sunrise  these  indications  hold 
but  with  opposite  meanings,  yet  for  such  an  opinion  the  writer  has 
never  been  able  to  find  any  support,  but  has  constantly  seen  good 
days  and  bad  days  follow  both  red  and  gray  sunrises. 

After  two  or  three  white  frosts ,  rain  may  be  expected.  This 
fact,  and  also  that  when  ditches  or  drains  smell  more  than  usually, 
rain  follows,-  has  long  been  familiar  to  all  persons  living  in  the 
country.  On  the  other  hand,  all  indications  drawn  from  changes 
in  the  moon’s  quarters,  position  of  the  crescent  moon,  etc.,  in  the 
sky,  certainly  amount  to  nothing. 

Changes  in  the  barometer  have  not  the  significance  in  this  hemi¬ 
sphere  which  they  have  in  the  other,  and  little  reliance  can  be 
placed  on  them. 

Finally,  it  should  be  observed  that  although  the  foregoing  in¬ 
dications  as  to  stillness  and  as  to  clearness  are  generally  reliable, 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  231 


it  cannot  be  affirmed  that  they  are  invariably  so ;  they  can  be 
depended  upon  as  showing  the  probable  course  of  the  weather, 
but  not  as  being  infallible. 

Before  terminating  these  observations  on  landscape  photogra¬ 
phy,  another  remark  needs  to  be  made.  In  the  very  highest 
class  of  landscape  prints  there  is  sometimes  seen  a  combination 
of  great  brilliancy  and  perfect  softness,  that  surprises  as  well  as 
charms,  and  leads  directly  to  the  question,  how  is  this  difficult 
combination  of  excellences  obtained  ?  Not  by  any  secret  process, 
that  we  know,  for  those  who  succeed  best  have  always  given 
their  formulae  freely ;  it  is,  therefore,  not  the  materials  used,  but 
the  mode  of  using  them,  that  is  the  essential  point. 

It  is  certain  that — 

Softness  is  promoted  by  length  of  exposure  and  rapidity  of  de¬ 
velopment. 

Brilliancy  is  heightened  by  shortness  of  exposure  and  slowness 
of  development. 

The  difficulty,  of  course,  is  that  what  promotes  the  one  object 
interferes  with  the  other,  and  this  is  why  so  few  fully  attain  both. 
There  is  only  one  way  in  which  it  can  be  done,  and  this  is  to  seek 
for  softness  by  length  of  exposure,  and  then  to  combine  this  with 
brilliancy  by  a  slow  development. 

In  practice :  Give  a  full  exposure  (using  a  fair  dose  of  bromide), 
such  that  with  an  ordinary  developer  the  picture  would  flash  up 
instantly.  So  developed,  the  picture  would  be  full  of  half-tone, 
but  flat  and  tame.  Therefore  add  water  and  acetic  acid  to  the  de¬ 
veloper  until,  notwithstanding  the  full  exposure,  the  image  comes 
out  gradually,  avoiding,  however,  all  exaggeration,  both  of  ex¬ 
posure  and  development,  and  combining  the  two  so  that  each 
shall  correct  the  other’s  faults. 

The  best  results,  however,  are  always  to  be  obtained  .by  the 
use  of  a  specimen  of  cotton  that  has  had  exactly  the  salting  that 
suits  it.  To  buy  pyroxyline  at  random,  even  from  the  best 
makers,  and  then  select  a  formula  for  salting  at  random,  even  if 
it  be  a  formula  of  the  highest  authority,  and  then  use  a  develop¬ 
ment  recommended  either  in  a  treatise  or  by  a  friend,  but  having 
no  definite  relation  to  the  cotton  and  salting,  is  to  put  the  chances 
against  a  full  success.  In  England  few  even  of  the  oldest  and 
most  skilful  landscape  photographers  make  their  own  collodion ; 
they  buy  ready  made  some  particular  sort  which  experience  has 


232 


PHOTOGRAPHIC  MANIPULATIONS. 


shown  them  to  suit  their  particular  way  of  working,  often 
habitually  and  systematically  mixing  the  collodion  of  two 
different  makers  in  certain  proportions.  The  collodion  maker 
manufactures  his  own  cotton,  which  he  keeps  as  uniform 
in  character  as  possible.  Very  long  experience  has  taught  him 
the  very  best  salting  for  it,  and  he  thus  delivers  a  collodion 
of  very  high  quality.  The  photographer  thus  gets  a  great  advan¬ 
tage  ;  in  our  system,  where  the  photographer  makes  his  own 
collodion,  he  for  the  most  part  gets  an  inferior  article,  even  with 
the  best  cotton,  unless  by  careful  experiment  (see  p.  132)  he  finds 
out  just  what  treatment  some  particular  cotton  requires,  and 
manages  it  accordingly.  This  troublesome  investigation  he  must 
either  make  for  himself,  or  else  pursue  his  work  under  telling 
disadvantages.  The  great  excellence  of  English  landscape  work 
is  partly  due  to  this  system  of  buying  collodion  instead  of  cotton, 
and  partly  to  the  character  of  the  light  in  that  country,  generally 
soft  and  broken,  with  little  of  the  burning  brilliancy  of  ours. 

The  brightness  of  the  print  will  also  largely  depend  upon  the 
albumenized  paper.  First-class  prints  will  always  need  first-class 
paper :  solid,  full-bodied  paper,  well  albumenized  with  sound, 
fresh  albumen,  and  paper  that  has  been  carefully  kept,  and  not 
too  long. 


§  6. — Toning  of  Landscape  Prints. 

Although  remarks  on  this  point  belong  technically  rather  to 
the  head  of  printing,  yet  they  are  so  closely  connected  with  the 
general  subject  of  Landscape  Photography,  that  I  have  preferred 
to  give  them  a  place  here. 

A  landscape  print  is  subject  to  none  of  the  conventional  rules 
of  color  that  hold  to  a  large  extent  with  portraits,  and  even  to 
some  extent  with  architectural  views.  Every  pleasing  tone  is 
appropriate — light  brown,  deep  brown,  warm  brown,  dark  purple, 
purple  black,  steel  gray,  and  pure  black.  All  of  these  do  well. 
Blue  black  is  unpleasing,  and  is  presumably  never  got  intention¬ 
ally,  but  results  from  accidental  over-toning. 

All  the  warm  shades  up  to  black  do  well,  as  has  just  been  said, 
and  a  wide  range  of  them  gives  a  most  agreeable  diversification 
to  a  collection  of  views.  It  will  be  found,  however,  that  every 
negative  has  some  particular  tone  that  gives  its  best  effects.  This  is  a 
fact  that  every  photographer  of  refined  artistic  taste  will  perceive 
and  feel:  it  becomes,  therefore,  in  the  highest  degree  desirable 


LANDSCAPE  AND  ARCHITECTURAL  PHOTOGRAPHY.  233 


to  be  able  to  say  approximately  of  any  negative  in  advance,  or 
on  seeing  the  first  proof  taken,  what  toning  will  best  suit  it.  The 
following  remarks  may  afford  some  clue  to  this  knowledge. 

Some  negatives  that  have  been  taken  with  a  highly  favorable 
illumination,  and  have  been  developed  exactly  right,  will  exhibit 
so  exquisite  a  combination  of  contrast  and  harmony  of  light  and 
shade,  that  they  will  look  well  with  any  toning.  They  have  no 
defects  to  soften,  and  can  hardly  be  spoiled  in  the  printing.  For 
this  higher  class  of  negatives,  a  rich  warm  purple  black,  best 
obtained  by  the  acetate  of  soda  or  by  the  benzoate  toning  bath, 
will  be  the  most  suitable. 

Starting  from  a  supposed  perfect  negative,  we  gradually  pass 
down  to  less  excellent  effects.  In  all,  we  shall  suppose  that 
both  the  denser  and  thinner  parts  are  full  of  detail  (for  if  either 
lacks  it  the  negative  will  not  be  worth  printing),  but  that  these 
parts,  though  each  full  of  detail,  do  not  work  well  together.  If 
the  printing  be  stopped  when  the  thinnei;  parts  are  right,  the 
denser  have  not  produced  their  best  effects ;  if  it  be  carried  on 
until  the  latter  are  right,  the  former  are  too  heavy  and  dark. 

Now,  this  is  a  fault  which  may  exist  in  every  variety  of  degree. 
If  it  exists  to  a  large  degree,  the  negative  is  worthless;  if  only  to 
a  slight  one,  the  intention  here  is  to  point  out  what  course  of 
action  will  render  such  a  fault  the  least  conspicuous. 

The  lighter  and  the  warmer  the  color,  the  less  this  bad  effect 
will  be  noticeable,  a  fact,  I  believe,  which  has  never  been  pointed 
out  before,  though  possibly  some  may  have  acted  on  it.  A  print 
must  be  exposed  until  the  detail  is  out  in  the  high  lights,  other¬ 
wise  it  is  a  complete  failure.  The  effect,  therefore,  of  the  dis¬ 
cordance  here  spoken  of,  is  always  to  produce  heavy  black 
shadows,  without  detail,  and  the  lighter  and  warmer  the  toning, 
the  less  offensive  will  be  these  dark  masses,  and  the  more  of  de¬ 
tail  will  be  left  in  them.  An  observation  of  this  rule  will  go  far 
towards  getting  a  fair  print  from  a  somewhat  faulty  negative.  But 
it  must  be  understood  in  the  clearest  way,  that  beyond  a  certain 
point  the  want  of  harmony  is  an  irretrievable  one. 

Conversely,  it  is  evident  that  if  a  negative  lack  contrast,  either 
from  the  subject  having  been  too  monotonously  lighted,  or  from 
an  over-exposure,  a  pure  black  toning,  without  too  much  over¬ 
printing,  will  do  what  can  be  done  towards  affording  a  good 
result. 

16 


234 


PHOTOGKAPHIC  MANIPULATIONS. 


If  these  precautions  be  neglected,  and  if,  for  instance,  a  nega¬ 
tive  in  which  the  contrast  is  already  too  great,  be  toned  up  to 
full  black,  the  result  will  be  that  its  faults,  instead  of  being 
softened,  will  be  aggravated.  And  if  the  photographer  is  un¬ 
aware  of,  or  does  not  appreciate,  the  principle  here  laid  down,  he 
may  never  obtain  more  than  a  passable  result  from  a  negative 
which,  properly  handled,  might  give  a  really  good,  though  not  a 
first-rate,  print.  Generally  an  acetate  toning  bath  will  be  found 
the  best  for  landscape  prints. 


CHAPTER  VIII. 

COMPOSITION. 

\  1.— Landscapes. 

Of  late  years  there  has  been  a  continually  increasing  realiza¬ 
tion  of  the  defects  and  incompleteness  of  landscape  photographs 
taken  with  entire  ignorance  of  the  principles  of  composition,  and 
it  is  becoming  well  understood  that  mere  technical  skill  cannot 
compensate  for  want  of  this  knowledge,  which,  even  in  a  very 
elementary  form,  is  found  to  be  invaluable.  So  that,  if  two 
persons,  the  one  having  some  knowledge  of  artistic  composition, 
and  the  other  ignorant  of  it,  undertake  to  photograph  the  same 
view,  the  former  will  always  be  enabled  to  make  the  best  choice 
of  the  point  at  which  to  plant  his  tripod. 

Cultivated  taste  has  learned  that  the  representation  of  a  land¬ 
scape  gives  a  completely  satisfying  effect  to  the  mind  most  easily 
by  complying  with  certain  general  conditions  which  have  been 
reduced  to  fixed  rules.  Too  slavish  a  compliance  with  these 
leads  directly  to  mannerism  and  sameness,  but  some  acquaint¬ 
ance  with  them  cannot  but  be  of  the  highest  use  to  every  intelli¬ 
gent  photographer. 

Line  of  Direction — Balance. — In  examining  any  picture,  we 
may  discern  certain  lines  of  direction.  These  lines  may  be  of 
one  prominent  object,  or  may  depend  upon  the  directions  of  the 
principal  portions  of  a  succession  of  objects. 

It  is  a  rule  that  these  lines  of  direction  should  support  each  other , 
as  in  Fig.  Ill,  where  the  longer  line  is  supported  by  the  shorter. 


COMPOSITION. 


235 


The  longer  line  may,  for  example,  be  that  of  a  distant  range  of 
mountains,  and  the  shorter  that  of  a  conspicuous  bough  of  a  tree, 
or  of  any  other  prominent  object  in  the  foreground;  or  both 
lines  may  depend  partly  upon  distant  and  partly  upon  near 
objects — it  is  immaterial.  The  essential  point  is  only  that  the 
characteristic  lines  of  the  picture  shall  balance  each  other.  But 


Fig.  111.  Fig.  112. 


if  the  lines  be  all  in  one  direction,  as  in  Fig.  112,  or  even  if  not 
quite  parallel,  there  is  a  want  of  balance,  and  the  idea  of  weak¬ 
ness  and  of  falling  is  given.  Moreover,  the  effect  of  the  repeti¬ 
tion  of  direction  is  generally  unpleasing,  though  it  is  occasionally 
used  to  convey  the  idea  of  receding  distance.  In  any  case,  how¬ 
ever,  it  is  necessary  that  these  lines  should  be  balanced. 

A  succession  of  perpendicular  (see  Fig.  113)  or  of  horizontal 
(Fig.  114)  lines  is,  for  the  most  part,  unpleasing.  As  an  example 

Fig.  113.  Fig.  114. 


of  the  former,  we  may  take  a  row  of  straight-stemmed  trees,  the 
effect  of  which  is  infinitely  less  pleasing  than  if  their  directions 
are  diversified.  Parallel  horizontal  lines  are  rarely  allowable; 
sometimes,  however,  they  are  employed  by  artists  in  “  parallel 
perspective” — that  is,  where  buildings  are  represented  in  full 
front  view. 

As  pictures  are  commonly  bounded  by  four  right  lines,  any 
arrangement  of  the  important  objects  in  a  picture  that  brings 
them  side  by  side,  and  at  equal  distances  from  the  base  line,  pro¬ 
duces  to  some  extent  the  parallelism  of  Fig.  114.  Similarly,  if 


286 


PHOTOGRAPHIC  MANIPULATION’S. 


they  are  directly  over  one  another,  they  form  parallels  with  the 
side,  as  in  Fig.  118.  The  same  principle  applies  also  to  the  in¬ 
troduction  of  a  tree  with  a  straight,  perpendicular  shaft,  near  to 
the  edge  of  a  picture.  It  falls  into  an  objectionable  parallelism 
with  the  side  line.  These  faults  are  to  be  borne  in  mind  and 
avoided. 


The  Diagonal  Line. — According  to  the  direction  into  which  the 
principal  lines  of  the  picture  fall,  the  composition  is  distinguished 

into  angular  and  circular.  The  diago¬ 
nal  line,  the  simplest  form  of  angu¬ 
lar  composition,  is  exceedingly  well 
adapted  for  representation  of  perspec¬ 
tive,  especially  when,  to  get  a  better 
range  of  effect,  the  distance  is  placed 
towards  one  side  of  the  picture. 

It  is  by  no  means  necessary  that  the 
principal  line  of  direction  should  pro¬ 
ceed  directly  from  one  angle  to  the  other.  This  angular  line 
of  direction  should  always  be  supported — that  is,  the  eye  carried 
along  it  should  not  be  dropped  vaguely,  but  fall  upon  some 
object,  which,  though  it  must  be  distinct,  need  not  be  large. 
This  object  is  termed  the  “  ruling  point.”  An  inspection  of  land¬ 
scapes  and  groups  executed  by  artists  will  show  how  far  inge¬ 
nuity  has  often  been  taxed  to  hit  upon  some  object  of  this  sort 
in  which  to  terminate  a  line  of  principal  direction.  In  country 
scenes,  a  dog,  or  a  fowl,  or  any  other  small  object  in  keeping 
with  the  general  subject,  will  be  introduced  into  the  foreground. 
A  little  examination  will  show  that  its  exact  position  has  been 
determined  by  a  line  of  principal  direction,  and  that  the  object 
has  been  placed  at  its  exact  intersection  with  the  ground.  The 
universality  of  this  practice  seems  to  indicate  that  it  is  correct ; 
the  principle  is  evidently  that,  after  the  eye  has  been  carried 
from  one  to  another  of  the  striking  features  of  a  picture,  it 
should  not  finally  fall  blankly  upon  nothing,  but  that  there  must 
be  some  sufficient  object  upon  which  to  rest.  In  most  cases  the 
resting  point  or  ruling  point  is  made  dark  on  a  lighter  ground, 
though  in  some  cases  a  lighter  object  than  those  that  surround  it 
is  used. 

A  beautiful  and  familiar  instance  of  the  balance  of  opposing 
lines  of  direction  is  seen  in  mountains,  the  opposite  sides  of  which 


COMPOSITION. 


237 


rest  against  each  other  thus:  A-  So  a  gap  between  two  moun¬ 
tains  gives  lines  that  balance  each  other  in  the  form  V- 

Circular  Composition. — Curved  lines  of  direction  are  often  intro¬ 
duced  with  very  fine  effect.  Views  of  lakes,  or  of  curved  reaches 
of  rivers,  will  be  apt  to  fall  into  this  form,  and  it  is  seen  in  many 
other  compositions  of  rural  scenery. 

The  Foreground. 

The  foreground  is  the  portion  generally  most  under  the  photo¬ 
grapher’s  control,  and  those  who  desire  to  obtain  the  greatest 
success  will  spare  no  pains  in  the  selection  of  this  part  of  their 
picture. 

The  foreground  should  be  diversified.  A  level,  unbroken  fore¬ 
ground  of  grass  or  meadow  cannot  be  expected  to  give  a  good 
effect.  It  weakens  the  effect  of  the  distance,  and  deprives  the 
picture  of  much  of  the  character  that  it  ought  to  possess. 

A  portion  of  the  foreground  should  be  occupied  by  some  dark 
object,  whose  effect  will  be  materially  enhanced  if  brought  into 
immediate  contrast  with  some  of  the  highest  lights  of  the  picture. 
The  best  effect  is  for  the  most  part  attained  by  placing  the  dark 
object  in  the  foreground  under  the  farthest  distance.  This  gives 
great  tenderness  and  softness  to  the  distance,  causes  it  to  recede 
from  the  foreground,  and  at  the  same  time  supports  it  by  lending 
firmness  and  foundation  to  it.  Too  much  attention  to  this  point 
cannot  be  given  by  the  landscapist,  who  will,  however,  often  have 
his  patience  and  ingenuity  taxed  to  the  uttermost  to  find  anything 
like  a  satisfactory  foreground  to  his  pictures. 

There  is  a  great  beauty  in  very  trifling  objects,  which  many 
habitually  overlook.  Bushes  and  vines,  rocks,  stones,  logs,  often 
have  elements  of  attraction  that  reveal  themselves  only  by  ob¬ 
servation  and  cultivation.  A  tasteful  arrangement  of  such  objects 
in  the  foreground  of  a  photograph  lends  to  it  an  inexpressible 
charm. 

The  writer  cannot,  perhaps,  find  a  more  striking  illustration 
than  in  a  clump  of  brambles.  To  many,  such  a  thing  would 
seem  to  be  so  essentially  ugly  that  it  should  be  excluded,  is  pos¬ 
sible,  whereas,  on  the  contrary,  it  is,  both  in  nature  and  in  repre¬ 
sentations  of  scenery,  almost  always  a  very  beautiful  object.  The 
stems  present  often  a  beautiful  combination  of  right  lines  and 
graceful  curves,  the  leaves  have  a  surface  that  sends  back  light 


238 


PHOTOGRAPHIC  MANIPULATIONS. 


enough  to  give  brightness  to  the  lights,  and,  by  contrast,  depth 
to  the  shadows.  Often  the  more  succulent  shoots  will  hang  over 
in  festoons  of  singular  gracefulness.  Late  in  the  autumn,  banks 
of  brambles  retain  their  leaves  long  after  the  trees  are  stripped, 
and  then,  if  they  can  be  introduced  into  a  picture,  they  are  most 
valuable. 

When  the  foreground  is  so  level  and  unbroken  that  no  diver¬ 
sification  can  be  introduced,  a  shadow ,  as  of  a  large  tree,  falling 
across  it,  at  once  relieves  the  tameness,  and  produces  a  beautiful 
effect. 

The  Distance. 

The  distance  should  never  find  its  place  exactly  in  the  middle 
of  the  picture,  which  by  such  a  disposition  becomes  divided,  as 
it  were,  into  two  equal  halves,  to  the  complete  destruction  of  its 
artistic  character.  In  fact,  no  important  object  should  be  placed 
exactly  at  the  centre  of  the  picture,  which  is  by  artists  considered 
to  be  a  “weak  point.”  Nor  should  any  important  object  be 
placed  exactly  upon  the  middle  line  which  divides  a  picture  from 
top  to  bottom  or  from  side  to  side.  Its  effect  will  be  always 
better  if  it  is  distinctly  removed  from  either  of  these  lines. 

A  peculiar  pleasure  is  given  when  the  eye  is  conducted  from 
the  foreground  to  the  distance  by  lines  of  direction.  These  lines 
may  be  one  or  both  banks  of  a  river  or  stream,  a  picturesque 
road,  or  other  object.  The  leading  should  be  rather  by  broken 
and  diversified  lines  than  by  straight  ones. 

A  certain  pleasure  is  communicated  when  objects  in  the  middle 
distance  are  repeated  in  the  farther  distance.  Such  a  repetition 
is  not  to  be  by  the  same  object,  but  rather  by  some  other  object 
in  strict  keeping.  This  rule  is  closely  allied  to  one  in  painting. 
It  is  laid  down  in  painting,  that  if  a  particular  color  be  introduced 
in  one  place  only,  it  has  the  effect  of  a  spot  or  blot ;  the  color 
must  be  carried  through  the  picture,  or  at  least  part  of  it,  by 
recurring  here  and  there.  As  in  colors,  so  in  objects.  If  trees 
are  seen  in  the  foreground  or  middle  distance,  the  eye  is  gratified 
by  seeing  them  reappear  in  the  distance.  If  a  cottage  or  other 
building  be  a  conspicuous  object  in  the  foreground,  the  eye  likes 
to  see  something  similar  in  the  distance. 

The  effect  of  a  high  light  in  the  extreme  distance  is  greatly 
enhanced  by  placing  a  dark  object  in  the  foreground,  somewhat 
under  it,  but  not  perpendicularly.  This  acts  partly  by  throwing 


COMPOSITION. 


289 


the  distance  farther  back,  and  thus  powerfully  aiding  the  impres¬ 
sion  of  distance,  and  partly  because  the  light  becomes  lighter  and 
the  darkness  darker  through  contrast. 

If  the  different  planes  of  distance  are  not  well  made  out  in  a 
photograph,  that  is,  if  they  do  not  appear  to  occupy  the  same 
relative  position  in  the  photograph  which  belongs  to  them  in 
nature,  the  fault  may  arise  from  the  use  of  too  small  a  stop, 
which  tends  to  produce  a  sort  of  map-like  effect,  or  from  the  use 
of  a  lens  of  too  short  or  too  long  a  focus.  In  the  first  case  the 
middle  distance  is  transferred  to  the  extreme  distance,  and  con¬ 
founded  with  it.  In  the  latter  case  the  middle  distance  is  forced 
forward  into  the  foreground.  (See  chapter  on  Perspective.) 

The  Skies. 

A  blank  white  sky  always  disfigures  a  photograph,  and  must 
be  avoided  if  possible.  Several  alternatives  present  themselves, 
one  or  other  of  which  should  be  adopted  whenever  possible. 

If  large  slow-moving  clouds  are  present,  they  may  sometimes 
be  caught,  especially  if  the  illumination  of  the  landscape  be  good, 
and  so  that  it  comes  out  rapidly,  and  without  a  prolonged  devel¬ 
opment,  which,  in  wet  plates,  always  thickens  up  the  skies. 
Large  stops  are  always  favorable  for  getting  clouds  with. 

If  clouds  cannot  be  taken  with  the  landscape,  they  may  be 
taken  separately  and  printed  in ,  for  which  directions  are  given 
elsewhere. 

But  it  is  an  excellent  plan  to  cover  as  much  as  possible  the  sky 
with  foliage  or  other  objects.  Large  trees  in  the  foreground  will 
aid  in  this.  In  hilly  countries  the  elevations  will  be  a  great  aid. 
In  level  districts  it  will  often  be  useful  to  raise  the  horizon  line. 
Fortunately  this  line  is,  in  landscapes,  very  much  under  control. 
In  architectural  subjects,  as  the  camera  must  always  be  hori¬ 
zontal,  we  can  only  effect  this  by  raising  the  camera  front,  or 
bringing  in  the  use  of  the  swing-back.  But  in  landscapes  with 
no  buildings  a  good  deal  of  tilting  may  be  done  without  evil 
effects.  The  horizon  line  is  thus  raised,  and  the  proportion  of 
sky  diminished. 

In  dry  plate  work  we  may  often  keep  the  sky  thin,  and  thus 
avoid  the  unpleasant  whiteness.  This  is  a  very  great  advantage, 
and  is  especially  to  be  obtained  with  collodio-bromide  plates,  a 
most  important  feature  of  that  process. 


240 


PHOTOGRAPHIC  MANIPULATIONS. 


Some  experienced  landscape  photographers,  who  know  the 
value  of  even  a  little  shading  to  the  sky,  adopt  regularly  the  fol¬ 
lowing  plan :  When  the  printing  is  done,  they  open  one-half  the 
back,  and  bend  the  sky  end  of  the  print  in  a  curve  backwards, 
and  so  hold  it  to  the  light ;  it  thus  becomes  somewhat  darkened, 
and  by  doing  this  skilfully,  the  shading  is  regular.  The  amount 
of  trouble  is  almost  nothing,  and  the  gain  decided.  The  writer 
believes,  from  an  inspection  of  prints  by  Bedford,  Sowlier,  and 
other  masters  of  the  art,  that  they  constantly  avail  themselves  of 
this  method. 


Position. 

The  whole  picture  is  generally  composed  with  reference  to 
some  one  important  object,  to  which  all  the  rest  stand  in  some 
more  or  less  definite  relation. 

Care  must  be  taken  that  this  object  (or  indeed  any  object  to 
which  it  is  intended  to  give  prominence)  shall  not  occupy  the 
centre  of  the  picture,  which  is  always  the  weakest  point  in  the 
whole.  Such  an  object  may  be  thrown  to  the  right  or  the  left, 
above  or  below ;  it  is  unimportant,  provided  it  be  kept  out  of 
the  centre.  If  the  conspicuous  object  improperly  placed  there 
be  small,  it  will  look  like  a  spot  or  blot ;  if  long,  as,  for  example, 
a  tree,  it  will  divide  the  picture  into  equal  right  and  left  halves. 

It  is  apt  to  be  a  blemish  if  an  object  be  represented  as  partly 
in  the  picture,  and  cut  off  by  its  edges :  it  is  true  that  to  some 
extent  this  is  unavoidable,  but  it  is  objectionable,  especially 
when  the  subject  so  cut  off  is  important. 

Thus,  if  in  a  landscape  a  river  is  seen  to  run  into  one  side,  and 
out  of  the  other,  a  peculiarly  unsatisfying  impression  is  left  upon 
the  eye,  which  is  removed  if  the  ends  of  the  river  are  concealed 
by  trees  in  the  foreground,  rising  ground,  buildings,  etc.  Trees 
themselves  are  often  unavoidably  cut  off  by  the  sides  and  top  of 
the  view.  This  is  supported  by  the  eye;  but  if  a  building  of  at 
all  a  conspicuous  character  appears  in  the  picture,  and  is  partly 
cut  off  by  the  edge,  the  effect  is  most  unpleasing.  With  the 
human  figure  this  is  still  worse. 

It  has  been  held  by  some  that  no  figure  should  be  introduced 
with  the  eyes  directed  at  objects  not  themselves  included  in  the 
picture,  and  it  cannot  be  doubted  that  the  unity  of  effect  is  broken 
by  the  spectator’s  attention  being  thus  drawn  away  from  the  ob¬ 
jects  represented. 


COMPOSITION. 


241 


It  is  still  worse  when  the  figures  are  represented  looking  at 
the  camera  itself.  This  is  the  commonest  of  mistakes.  At  the 
moment  of  taking  the  picture  the  camera  is  of  course  the  central 
point  of  interest  to  all  present,  and,  unless  expressly  cautioned 
by  the  photographer,  any  person  who  is  in  sight  will  inevitably 
be  found  to  rest  his  eyes  on  that  instrument.  In  a  great  many 
cases  the  figure  will  give  a  better  effect  if  the  back  or  side  is 
turned  to  the  camera.  Let  us  suppose  that  we  are  looking  over 
the  brow  of  a  hill,  upon  a  lake  or  river  below.  A  figure  in  the 
foreground,  resting  against  a  tree,  and  apparently  contemplating 
the  scene,  will  have  an  infinitely  better  effect  than  one  apparently 
watching  those  operations  which  it  is  the  special  object  of  the 
photographer  to  avoid  recalling.  In  the  one  case  the  figure 
draws  attention  to ,  in  the  other  from ,  the  subject  of  the  picture. 

The  figure  itself  should  be  thoroughly  in  keeping  with  the 
scene.  Just  as  a  neat  trim  villa  is  a  particularly  uninteresting 
subject  for  a  picture,  so  a  carefully  dressed  person  looks  com¬ 
pletely  out  of  place  in  any  rural  scene  that  is  worth  planting  the 
camera  before.  A  laborer,  a  pedestrian  carelessly  dressed,  country 
children,  these  are  figures  in  keeping  with  the  subject.  If  a  river 
or  a  lake  form  part  of  the  picture,  a  man  fishing  or  wading  will 
add  to  the  life  of  the  scene,  but  his  appearance  must  correspond 
with  surrounding  objects. 

Generally  speaking,  whatever  is  neat,  trim,  and  elegant,  is  dis¬ 
pleasing  in  any  view  of  natural  scenery.  A  handsome  carriage 
introduced  into  the  picture  will  look  absurd — a  farmer’s  cart 
wiil  probably  be  in  place  and  a  great  help.  It  is  not  so  much 
the  object  itself,  as  its  condition.  A  new  market  wagon,  for  in¬ 
stance,  with  a  glazed  top,  would  spoil  any  picture.  An  ele¬ 
gantly  shaped  and  prettily  painted  skiff  may  look  absurd,  an 
old  barge  or  canal-boat  will  be  appropriate  and  pleasing.  A 
gentleman  in  a  dress  coat,  with  a  cane,  a  lady  with  flowers  and  a 
parasol,  introduced  into  any  country  scene,  will  spoil  all  our  satis¬ 
faction  in  observing  it,  whilst  appropriate  figures  will  be  always 
useful ;  the  rule  that  such  figures  must  not  look  towards  the 
camera  is  never  to  be  forgotten. 

ISTor  should  the  figures  be  placed  in  too  close  juxtaposition 
with  the  objects  of  principal  interest,  from  the  effectiveness  of 
which  they  would  tend  to  detract,  whereas  in  weak  points  of  the 
picture  they  will  prove  a  positive  benefit.  They  should  always 
assume  easy  attitudes,  and  such  as  will  not  be  ungraceful  or  ridi- 


242 


PHOTOGRAPHIC  MANIPULATIONS. 


culous.  The  writer  has  seen  an  otherwise  very  pretty  photo¬ 
graph,  in  which  was  a  male  figure  reclining  on  the  ground.  As 
the  face  was  towards  the  camera,  the  body  was  foreshortened,  and 
the  one  conspicuous  object  about  him  was  the  soles  of  his  boots, 
which  exactly  faced  the  spectator,  and  which,  by  reason  of  the 
violent  perspective  of  a  short-focus  lens,  appeared  greatly  in¬ 
creased  in  proportionate  size.  Such  errors  need  only  to  be  under¬ 
stood  to  be  shunned. 


The  Horizon. 

It  is  always  in  the  power  of  the  photographer  to  place  the 
horizon  where  he  will.  If  there  be  no  subjects  presenting  per¬ 
pendicular  lines,  the  camera  may  be  tilted  at  will ;  if  there  be, 
the  sliding  front  may  be  raised  or  lowered,  or  inclination  of  the 
lines  resulting  from  tilting  may  be  cured  by  the  use  of  the  swing- 
back. 

Raising  the  horizon  line  will  often  increase  the  beauty  of  the 
picture,  but,  it  must  be  confessed,  somewhat  at  the  expense  of 
truth.  If  a  perfectly  correct  delineation  of  any  scene  be  desired, 
the  camera  must  be  levelled.  Raising  or  depressing  the  camera, 
entirely  alters  the  relative  inclinations  of  natural  objects.  Thus, 
if  a  road  descends  a  hill,  it  will  equally  descend  in  the  picture  if 
the  camera  be  levelled,  but  the  writer  has  seen  such  a  road  repre¬ 
sented  in  a  negative  as  perfectly  level,  the  whole  descending  effect 
having  been  obliterated  by  inclining  the  camera  downwards. 
This  raises  the  horizon  line,  and  with  it  all  the  objects  beyond 
the  foreground. 

Where  the  object  of  the  photograph  is  simply  to  produce  a 
beautiful  picture,  it  is  perfectly  allowable  to  modify  and  improve 
the  scene  in  any  way  that  we  can.  But  where  a  truthful  repre¬ 
sentation  is  desired,  the  greatest  care  will  be  needed.  There 
exists  a  mistaken  idea  that  photographs,  being  taken  by  mechani¬ 
cal  means,  are  necessarily  correct  representations  of  natural  ob¬ 
jects,  and  they  are  consequently  offered  and  received  as  absolute 
proof  in  courts  of  law,  whereas  nothing  is  easier  than  to  create 
false  impressions  with  the  aid  of  photography.  No  delineation 
of  natural  objects  is  correct  unless  made  with  a  lens  of  not  less  than 
ten  nor  more  than  twenty  inches  in  focal  length,  with  a  levelled 
camera ,  and  with  a  centrally  stopped  lens.  And  before  any  photo¬ 
graph  is  received  in  evidence,  the  photographer  ought  to  be  re¬ 
quired  to  testify  as  to  these  points;  at  least  this  is  true  when  the 


COMPOSITION-. 


243 


question  depends  upon  relative  size  or  position.  Of  course,  if  the 
question  is  simply  as  to  the  existence  or  non-existence  of  some 
particular  object,  the  objections  here  stated  do  not  exist. 

It  is  an  axiom  with  artists  that  the  horizon  lines  should  never 
come  across  the  middle  of  the  picture  and  divide  it  into  two  equal 
halves,  but  always  above  or  below  it.  From  what  has  been 
already  said  it  will  be  evident  that  in  photographs  the  horizon 
line  will  be  more  frequently  above  than  below  the  middle. 

Contrast. 

Some  of  the  highest  pleasures  which  the  eye  is  capable  of  en¬ 
joying  depend  upon  contrast.  Contrast  is  of  various  kinds.  Of 
light ,  where  the  artist  throws  his  deepest  darkness  against  his 
highest  light,  thus  strengthening  both.  Of  size ,  as,  for  example, 
where  the  greatness  of  the  majestic  oak  is  made  more  apparent 
by  the  shrubs  or  bushes  at  its  base.  Of  form ,  as  where  the  grand 
elevation  of  the  mountain  is  further  ennobled  by  the  level  lake 
or  plain  at  its  foot.  Of  character,  as  when  the  graceful  lines  of 
pine-trees  are  contrasted  with  rugged  roughness,  as  in  Alpine 
hills,  or  where  slight  and  tender  vines,  with  delicate  tracery,  are 
seen  clinging  to  strong  trees  or  to  the  rocky  sides  of  hills,  or  are 
contrasted  with  the  rigid  lines  of  architecture.  Of  season ,  as 
when  winter  snows  look  down  from  the  mountain  upon  summer 
verdure  in  the  valleys  beneath.  Of  mass ,  as  when  light  clouds, 
the  lightest  of  all  visible  objects,  rest  upon  mountains,  which,  of 
all  natural  objects,  give  the  most  striking  effect  of  weight.  In  a 
word,  the  beauty  of  contrast  is  that  which  most  completely  per* 
vades  all  nature.  All  our  ideas  are  formed  by  comparison,  and 
contrast  is  comparison  in  its  most  vigorous  form. 

The  brightest  objects  in  a  picture  should  not  be  too  far  from 
the  centre.  If  placed  close  to  an  edge,  the  effect  is  very  objec¬ 
tionable.  The  tendency  of  a  picture  should  be  to  converge  atten¬ 
tion  to  the  centre,  not  to  scatter  it  towards  the  edges. 

Repetition. 

The  repetition  of  lines  of  direction,  as  has  been  already  said, 
is  for  the  most  part  unpleasing,  and  this  holds  with  both  groups 
and  landscapes. 

But  the  repetition  of  objects  themselves  is  often  very  pleasing 
The  echoing  of  a  near  object  by  a  distant  one  has  been  already 


244 


PHOTOGRAPHIC  MANIPULATION’S. 


spoken  of,  but  perhaps  the  greatest  beauty  of  repetition  is  where 
we  see  objects  mirrored  in  calm  water.  Few  persons  are  so  utterly 
destitute  of  the  sense  of  the  beautiful  as  not  to  appreciate,  how¬ 
ever  imperfectly,  the  charm  of  this  exquisite  reflection.  The 
commonest  object  may  in  this  way  be  rendered  beautiful  and 
attractive.  A  log,  a  branch,  a  boat,  insignificant  in  themselves, 
immediately  acquire  a  charm  by  being  repeated  in  the  water. 
Often  the  inversion  that  accompanies  reflection  materially  adds 
to  the  charm  by  the  variety  which  it  affords,  or  by  forming,  as  a 
reflection  often  does  when  looked  on  in  connection  with  the 
object  itself,  a  charming  symmetrical  figure. 

Atmospheric  Effect. 

When  a  scene  in  nature,  embracing  objects  at  various  distances 
from  the  spectator,  is  depicted  upon  a  flat  surface,  we  are  enabled 
to  distinguish  between  objects  near  and  distant,  in  two  different 
ways. 

One  of  these  is  Linear  Perspective ,  treated  of  elsewhere.  By 
virtue  of  it,  distant  objects  are  diminished  in  size  and  brought 
closer  together,  thus  giving  to  the  eye  the  information  that  they 
are  proportionately  remote. 

But  the  effect  of  linear  perspective  is  greatly  enhanced  by 
another  agency,  to  which  the  name  of  aerial  perspective,  or, 
better,  atmospheric  effect,  has  been  given. 

The  atmosphere  in  its  usual  conditions  is  not  wholly  transpa¬ 
rent,  but  interposes  an  exceedingly  delicate  veil,  imperceptible 
indeed  as  respects  neighboring  objects,  but  becoming  more 
evidently  distinguishable  as  the  distance  increases.  The  eye  is 
thus  greatly  aided  in  judging  distances,  which  it  unconsciously 
computes  by  the  extent  to  which  the  softening  effect  of  the 
atmosphere  reaches. 

If  this  softening  effect  of  the  atmosphere  be  studied,  it  will  be 
found  to  act  as  follows  : — 

1.  It  diminishes  contrasts.  Dark  shadows  lose  something  of 
their  darkness,  high  lights  of  their  brightness.  This  opposite 
effect  of  the  atmosphere  on  light  and  on  shade  needs  some  ex¬ 
planation.  Lights  lose  part  of  their  brightness  by  reason  of  the 
slight  opacity  of  the  atmosphere  through  which  they  pass.  But 
the  darkness  of  the  shadows  is  lessened  by  the  light  which  falls, 
not  on  them,  but  on  the  atmosphere  through  which  they  are  vievjed. 


COMPOSITION. 


245 


We  have  a  familiar  example  of  this  in  the  sky  itself,  which  is 
only  the  deep  shadow  of  the  outer  darkness  of  space  viewed 
through  a  not  perfectly  transparent  medium,  which  medium  is 
itself  lighted  up  by  the  sun,  and,  under  a  well-known  physical 
law,  diffuses  the  more  refrangible  or  violet  rays,  and  transmits 
the  rays  belonging  to  the  less  refrangible  end  of  the  spectrum. 
In  clear  weather  the  sky  is  deepest  in  color,  because  there  is  less 
opacity  in  the  atmosphere  to  receive  and  reflect  the  sun’s  light. 
On  a  high  mountain  the  sky  is  darker  still,  and  at  very  great 
elevations  appears  almost  black. 

2.  It  obliterates  details.  Smaller  objects  and  parts  of  objects 
easily  distinguishable  when  near  by,  cease  to  be  so  in  proportion 
to  the  distance  to  which  the  object  is  removed,  and  of  this  the 
eye  takes  due  note  and  recognizes  the  cause. 

3.  It  softe7is  outlines.  The  dead  limb  of  a  tree  near  by,  for  ex¬ 
ample,  cuts  boldly  and  sharply  on  the  sky,  but  the  outline  of  a 
trunk  upon  a  hill  in  the  middle  distance  is  already  somewhat 
softened,  and  the  outlines  of  distant  mountains  are  still  more  so. 

Consequently,  atmospheric  effect  tends  to  give  soft  grays  and 
middle  tints  to  distant  objects,  and  to  efface  all  sharp  contrasts  of 
light  and  darkness.  Lines  also  cut  each  other  less  sharply.  In 
nature  we  find  a  very  wide  range  of  variety  as  to  this  influence. 
When  the  air  is  very  free  from  moisture,  as  on  some  of  the  arid 
plains  at  the  base  of  the  Rocky  Mountains,  atmospheric  effect 
almost  disappears,  and  distant  objects  appear  unnaturally  and  de¬ 
ceptively  near.  It  is  not  too  much  to  say  that  the  capacity  of  the 
eye  for  judging  correctly  of  distances  is  actually  destroyed.  From 
this  extreme  we  may  pass  through  every  degree  to  the  other, 
when  the  air  is  so  laden  with  mist  that  near  objects  seem  farther, 
and  distant  objects  disappear  altogether. 

It  is  a  curious  fact,  and  one  of  the  highest  importance  for  the 
photographer  to  understand,  that  both  the  process  which  he  uses 
and  his  lenses  themselves  may  have  a  great  influence  on  the 
amount  of  atmospheric  influence  which  will  appear  in  his  pictures. 

The  tendency  of  the  ordinary  wet  process  is  to  give  a  mode¬ 
rate  amount  of  atmospheric  effect.  The  dry  processes  differ 
extremely  in  this  respect,  according  to  the  preservative  used. 
Thus  tannin,  cloves,  coffee,  gallic  acid,  and  similar  preservatives 
tend  to  diminish  atmospheric  effect,  whilst  gum  has  the  very 
valuable  property  of  enhancing  it  in  quite  a  remarkable  way,  and 


246 


PHOTOGRAPHIC  MANIPULATIONS. 


thus  becomes  a  most  valuable  adjunct  to  other  preservatives, 
though,  when  well  managed,  it  is  capable  of  acting  well  alone. 

The  lens  has  likewise  something  to  do  with  this  rendering, 
though  its  action  has  been  by  some  writers  a  good  deal  exagge¬ 
rated  ;  it  is  the  size  of  the  diaphragm  used  that  has  more  to  do 
with  the  atmospheric  effect  than  the  lens  itself. 

A  large  diaphragm  will  always  tend  to  increase ,  a  small  one  to 
diminish ,  aerial  perspective.  This  is  caused  in  two  distinct  ways, 
co-operating  to  the  same  result.  For  a  small  diaphragm  will 
always  greatly  increase  the  depth  of  focus,  so  that  when  the  focus 
has  been  taken,  as  it  always  must  be,  on  near  objects,  a  small 
diaphragm  will  cause  the  distance  to  be  in  sharp  focus  also.  This 
will  increase  the  detail  of  the  distance,  and,  as  it  has  been  already 
shown  that  one  way  in  which  atmospheric  effect  shows  itself  is  in 
tending  to  obliterate  detail,  the  greater  depth  of  focus  necessarily 
tends  to  counteract  the  effect  of  the  atmosphere.  Again,  a  small 
diaphragm  always  tends  to  harshness  of  contrast,  and  it  has  been 
also  shown  that  aerial  perspective  especially  shows  itself  by 
diminishing  contrast.  Clearly,  therefore,  aerial  perspective  will 
be  produced  in  direct  proportion  to  the  size  of  the  diaphragm. 
This  explanation  tends  to  throw  additional  light  upon  the  fact 
stated  in  a  previous  chapter,  that  a  large  stop  materially  aids  the 
effect  of  distance  by  placing  objects  in  their  proper  planes  of 
distance  from  the  eye. 

It  is,  however,  sufficiently  apparent,  from  what  has  been  pre¬ 
viously  said,  that  lenses  will  differ  somewhat  amongst  themselves, 
independently  of  the  diaphragm,  as  to  the  rendering  of  atmos¬ 
pheric  effect,  inasmuch  as  some  have  greater  depth  of  focus  than 
others. 

Those  photographers  who  are  accustomed  to  plant  their  cameras 
in  front  of  any  conspicuous  object,  satisfied  if  it  covers  enough  of 
their  plate,  and  if  they  can  get  a  clean  negative  of  it,  will  natu¬ 
rally,  in  the  same  spirit,  endeavor  to  get  the  same  sharpness  in 
the  distance  (so  far  as  practicable)  as  in  the  foreground.  Such 
will  be  found  working  with  small  diaphragms,  and  acid  baths, 
and  getting  technically  perfect  negatives,  which  will  yield  prints 
that  no  one  cares  to  look  at  a  second  time,  prints  in  which  the 
foreground  lies  flat  upon  the  middle  distance,  and  both  on  the 
extreme  distance,  which,  instead  of  striking  the  eye  at  once  with 
a  unity  of  effect,  have  to  be  looked  at  attentively  before  the  rela- 


COMPOSITION. 


247 


tions  of  the  different  parts  explain  themselves — in  a  word,  prints 
which  are  a  reproach  to  photography. 

It  must  at  the  same  time  be  very  clearly  understood  that  the 
writer  is  as  far  as  possible  from  wishing  to  say  that  a  photo¬ 
graphic  landscape  should  show  a  clean  cut  foreground,  and  a 
hazy,  woolly-looking  distance.  No  rules  must  be  carried  to 
excess,  or  the  truth  and  beauty  that  result  from  them  are  de¬ 
stroyed  by  exaggeration.  That  objects  several  miles  away  should 
be  as  distinct  and  sharply  cut  as  those  near  at  hand,  is  unnatural, 
or  at  least  occurs  in  certain  regions  and  in  peculiar  states  of  the 
atmosphere  only,  with  which  we  have  not  here  to  do.  It  cannot 
be  right,  therefore,  and  it  certainly  is  not  pleasing  to  an  educated 
eye,  that  they  should  be  so  represented  in  a  photograph  or  in  any 
other  form  of  delineation.  As  already  said,  the  landscape  painter, 
with  this  matter  under  his  absolute  control,  always  softens  the 
distance. 


g  2. — Portraiture. 

What  has  been  said  in  the  foregoing  section  finds  its  natural 
application  also  to  portraiture.  Lines  must  be  balanced  and  sup¬ 
ported  ;  light  must  be  brought  out  by  opposing  it  to  shade,  in 
portraiture  as  in  landscape  work. 

To  give  an  agreeable  and  graceful  effect  to  a  single  standing 
male  figure,  has  always  been  a  difficulty  which  has  taxed  the 
genius  of  artists  to  evade.  When  a  man  clothed  in  our  modern 
habiliments  stands  erect,  the  lines  of  his  arms  and  legs  fall  into 
parallelism  with  his  body,  and  the  objectionable  effect  of  parallel 
perpendicular  lines  has  been  already  pointed  out  (Fig.  113).  There 
is  perhaps  no  effectual  way  by  which,  in  our  ordinary  portrait, 
this  difficulty  can  be  disposed  of,  unless  some  characteristic  occu¬ 
pation  or  position  can  be  adopted.  A  soldier,  for  example,  may 
rest  upon  his  musket,  a  fisherman  may  have  his  rod  so  disposed 
as  to  afford  a  supporting  line,  and  so  on ;  but  as  the  great  mass  of 
those  who  present  themselves  to  be  represented  by  the  camera  .ek> 
not  care  to  figure  in  connection  with  any  particular  vocation,  it 
follows  that  for  the  most  part  the  best  that  can  be  done  is  to  adopt 
a  sitting  posture,  not  in  profile  unless  the  back  legs  of  the  chair 
can  be  supported,  and  try  to  relieve  this  by  surrounding  objects. 
Good  effects  are  often  obtained  by  representing  the  sitter  as  either 
engaged  in  some  occupation,  reading,  playing  on  some  instru- 


248 


PHOTOGRAPHIC  MANIPULATIONS. 


ment,  examining  some  object,  or,  often  better,  as  baying  jnst 
turned  from  having  so  done. 

When  several  male  figures  are  introduced  together,  their  lines 
may  be  made  to  support  each  other ;  but  here,  again,  a  photo¬ 
graphic  difficulty  is  introduced — the  necessity  of  keeping  the 
heads  to  a  certain  extent  in  the  same  plane  of  distance. 

The  ingenuity  of  the  photographer  will  often  be  here  taxed 
to  a  severe  extent.  He  may  be  aided  by  the  following  obser¬ 
vations  : — 

Where  two  or  three  heads  are  present,  they  should  rarely  be 
placed,  as  so  very  often  seen,  on  the  same  level,  but  should  form 
a  pyramidal  arrangement,  or  else  fall  into  the  diagonal  line.  Or 
the  middle  head  may  be  the  lowest.  If  a  fourth  head  be  intro¬ 
duced,  it  may  either  fall  into  one  of  the  lines  of  the  above  forms, 
or  the  lozenge-shaped  composition  may  be  adopted.  If  more 
than  these  are  present,  they  may  either  have  a  place  in  the 
principal  arrangement,  or  a  secondary  group  may  be  formed.  It 
is  always  to  be  remembered  that,  in  obedience  to  the  exactions 
of  the  lens,  the  farthest  figure  must  be  also  the  most  central. 

A  group  of  three  persons  will  generally  be  the  most  manage¬ 
able.  Somewhat  less  so  with  two  or  four.  When  the  number 
increases,  difficulties  are  multiplied ;  when  it  diminishes  to  one, 
the  difficulties  of  getting  a  satisfactory  attitude  are,  as  already 
said,  most  serious.  A  standing  portrait  of  a  man  gives  almost 
invariably  the  effect  of  a  person  placed  for  the  express  purpose 
c>f  having  his  picture  taken,  and  this  is  apt  to  be  made  worse  by 
the  conscious  look  generally  assumed  by  the  person. 

The  same  remarks  apply,  though  to  a  somewhat  less  extent,  to 
female  portraits.  The  form  of  the  dress  considerably  relieves 
the  difficulty,  as  it  represents  two  opposing  inclined  lines  which 
tend  to  support  each  other.  Nevertheless,  single  portraits  of 
standing  female  figures  are  apt  to  bear  a  stiff  appearance,  unless 
in  the  hands  of  very  artistic  photographers.  When  sitting, 
however,  this  is  wholly  changed.  The  drapery  can  be  very  much 
varied,  and  a  great  support  can  be  got  by  regulating  the  folds  of 
the  dress  so  that  these  shall  run  in  directions  which  shall  relieve 
and  support  the  other  lines  of  the  picture — that  is,  that  some  of 
the  lines  of  drapery  shall  oppose  and  support  the  lines  produced 
by  the  direction  of  the  body,  the  position  of  the  arms,  &c.  The 
position  of  the  arms  can  often  be  regulated  in  sitting  figures, 
both  of  men  and  women,  to  greatly  aid  in  balancing  the  lines  of 


COMPOSITION-. 


249 


the  body ;  and  here  a  thousand  expedients  come  in  to  give  occu¬ 
pation  to  the  arms  and  explain  their  position. 

In  groups  of  female  figures,  or  of  men  and  women  together, 
the  same  remarks  as  those  made  respecting  the  positions  of  the 
heads  for  men  of  course  apply. 

Two  useful  observations  remain  to  be  made  before  we  close 
this  very  brief  section  on  an  important  subject. 

The  lines  which  connect  the  heads  of  a  group,  form  always  the 
principal  lines  of  the  picture.  Such  lines  should  never  be  per¬ 
mitted  to  simply  run  out  and  end  in  nothing,  but  when  carried  by 
the  eye  to  the  bottom  of  the  picture,  should  fall  on  some  object, 
precisely  as  alread}?-  explained  in  landscape  composition.  Thus, 
if  a  line  of  direction,  when  extended  by  the  eye,  reaches  a  table, 
for  example,  at  the  point  of  intersection  there  should  be  placed 
some  small  but  very  distinct  object,  dark  on  a  light  ground,  or 
light  on  a  dark  ground.  A  book,  an  open  letter,  or,  still  better, 
some  object  characteristic  of  the  taste  or  occupations  of  one  or 
more  of  the  sitters,  will  be  suitable.  If  a  line  of  direction  reach 
the  floor  or  a  wall,  the  same  principle  of  course  holds  good. 

Again,  a  line  in  some  parts  of  the  picture,  whose  direction 
crosses  that  of  the  main  line  of  the  picture,  will  give  an  excellent 
effect  by  supporting  it.  This  line'  may  be  anything,  a  cane  or 
staff,  any  object  whatever,  even  the  line  of  an  arm.  It  need  not 
cross  the  line  of  direction,  only  so  that  its  direction  does  so. 

Thus,  let  A,  j 5,  C ',  be  the  heads  of  any  group.  A  B  will  be  the 
most  important  line,  opposed  and  balanced  by  A  G.  But,  also, 


Fig.  116. 


A 


c 


JF 


some  other  line,  D  E ,  if  introduced,  will  greatly  support  the  line 
A  B  and  balance  the  picture.  And  where  the  line  A  B,  if  con¬ 
tinued,  would  terminate  at  F,  on  the  ground  or  elsewhere,  there 
should  be  some  object  for  it  to  rest  upon,  as  explained  above. 


17 


250 


PHOTOGRAPHIC  MANIPULATIONS. 


§  3. — Influence  of  Light.1 

Our  perception  of  the  inequalities  of  surface,  of  relative  distance, 
and  in  fact  of  the  shape  and  position  of  bodies  generally,  de¬ 
pends  almost  wholly  upon  light  and  shadow. 

Take,  for  example,  an  outline  drawing  of  a  building.  The 
eye,  chiefly  by  habit  and  education,  understands  that  a  solid 
body,  and  not  a  flat  surface,  is  intended  to  be  depicted.  I  say, 
the  eye  understands ,  for  it  seems  more  like  a  deduction  than  a 
perception. 

If  now  the  artist  washes  in  even  only  a  single  shade  of  neutral 
gray  behind  each  projection,  how  these  projections  suddenly  start 
out  and  strike  the  eye!  As  if  by  magic,  the  whole  building  has 
assumed  a  visible  solidity,  and  if  the  work  has  been  correctly 
performed  and  the  shades  duly  graduated,  the  eye  instantly  recog¬ 
nizes  the  length,  breadth,  and  height  of  the  edifice,  and  is  able 
to  derive  whatever  pleasure  its  justness  of  form  is  fitted  to  afford. 

Any  photographer  who  frequently  passes  a  public  building 
with  many  projections,  such  as  are  especially  to  be  found  in 
Gothic  architecture,  and  who  will  stop  and  carefully  study  the 
effects  of  different  lights  upon  it,  will  be  amply  repaid,  and  will 
learn  more  by  a  few  minutes  given  twenty  or  thirty  times,  or  still 
oftener,  than  by  a  year’s  random  photographing. 

At  times  the  light  is  so  exceedingly  uniform  and  so  broken  by 
clouds,  that  every  portion  of  a  building  will  be  almost  equally 
lighted.  So  far  from  this  being  an  advantage,  the  structure  will 
be  found  on  critical  examination  to  look  extremely  flat  and  tame, 
and  if  photographed  in  such  a  light,  its  photograph  will  also  be 
deficient  in  relief.  This  great  uniformity  of  light  may  occur  with 
various  amounts  of  illumination,  and  though  more  common  in 
dark  weather,  will  sometimes  be  seen  when  the  light  is  tolerably 
good. 

When  the  clouds  are  thinner,  a  considerable  quantity  of  direct 
light  (without  notable  sunshine)  may  pass  through  them.  In 
this  case  projections  cast  faint  shadows,  and  the  relief  is  greatly 
improved. 

With  still  thinner  clouds,  faint  sunshine  passes  through.  The 
inestimable  value  of  a  very  faint  sunshine  every  experienced  pho¬ 
tographer  will  fully  recognize.  Photographs  of  natural  scenery, 


See  also  ante ,  Remarks. on  causes  of  unsatisfactory  results  in  portraiture. 


ON  COPYING. 


251 


taken  in  the  absence  of  sunlight,  are  apt  to  be  tame  and  monoto¬ 
nous.  A  faint  sunlight  gives  an  exquisite  relief  and  life  to  the 
whole,  with  beautifully  illuminated  shadows. 

When  the  sun  is  fully  out,  and  especially  towards  the  middle 
of  the  day,  the  contrasts  become  excessive,  and  before  the  details 
in  the  shadows  impress  themselves,  the  high  lights  suffer. 

The  case  of  a  building  has  been  chosen  as  an  example,  but 
precisely  the  same  holds  good  with  portraiture.  The  shape  of 
features,  the  character  and  expression  of  the  face,  all  these  depend 
upon  light  and  shade  and  their  due  management.  ^ 

In  examining  the  work  of  professed  portraitists,  we  constantly 
observe  the  faults  here  pointed  out  as  being  so  easily  seen  and 
judged  in  a  building,  which  last,  from  its  invariable  position 
and  (so  to  speak)  expression,  enables  us  to  compare  the  effects  of 
different  lights  st>  very  advantageously.  These  faults  lie,  on  the 
one  side,  in  too  uniform  a  lighting,  by  which  the  features  are 
rendered  flat  and  the  expression  stupid,  or  at  least  less  intelligent 
than  the  original;  and,  on  the  other,  in  too  great  contrast  of 
lighting,  whereby  the  character  of  the  features  is  exaggerated, 
and  the  expression  rendered  stern  and  hard. 

These  two  generic  faults  represent  the  Scylla  and  Charybdis 
of  the  portraitist,  and,  with  the  varying  lights  of  the  day,  will 
require  his  most  intelligent  efforts  to  avoid. 


CHAPTER  IX. 

ON  COPYING. 

Copying  by  photography  falls  into  three  classes : — • 

1.  Copying  oil  paintings  and  drawings  in  color. 

2.  Copying  mezzotints  and  lithographs,  and  drawings  in 

Indian  ink  and  sepia,  &c. 

3.  Copying  line  engravings,  wood-cuts,  pen  and  ink  drawings, 

and  pencil  drawings. 

These  three  classes  will  require  different  treatment,  but  all  the 
varieties  in  one  and  the  same  class  will  require  the  same,  or 
nearly  the  same,  management. 

Old  oil  paintings,  in  which  the  backgrounds  have  become  very 


252 


PHOTOGRAPHIC  MANIPULATIONS. 


dark  and  the  colors  have  lost  their  brilliancy,  are  especially- 
difficult  to  copy;  in  fact,  in  many  cases,  it  will  be  impossible  to 
obtain  really  satisfactory  results. 

The  best  instructions  that  can  be  given  are,  to  use  a  pretty 
wide  stop,  give  a  long  exposure,  and  use  a  collodion  containing 
equal  parts  of  bromides  and  iodides.  (See  also  Chapter  XV., 
Remarks  on  keeping  plates.) 

In  the  second  class  above  enumerated,  we  included  subjects 
which,  though  in  monochrome,  present  gradation  of  tint.  These 
will  require  to  be  treated,  through  all  the  stages,  very  much  as 
views,  and  with  the  same  care  to  avoid  harshness  and  excess  of 
contrast. 

On  the  contrary,  the  third  class  will  require  a  widely  different 
treatment.  With  these  the  object  will  be  to  get,  not  to  avoid, 
strong  contrasts.  The  originals  are  composed  of*  only  white  and 
black,  the  half-tints  depending  upon  the  presence  of  more  or 
less  of  each  of  these  constituents.  A  white  and  black  negative 
will  therefore  be  wanted. 

But  it  is  an  entire  mistake  to  suppose,  as  was  for  a  long  time 
believed,  that  this  was  best  accomplished  by  the  use  of  a  collo¬ 
dion  containing  little  or  no  bromide.  The  author  of  this  book 
long  since  pointed  out  that  copying  was  best  done  with  ordinary 
landscape  collodion.  Iodide  of  silver  is  more  sensitive  to  a  strong 
light,  bromide  to  a  weak  light.  Now,  as  line  engravings  require 
to  be  copied  with  a  very  small  stop,  the  light  is  always  weak, 
consequently  bromide  is  needed;  and  this  view  is  fully  supported 
both  by  direct  experiment  and  by  common  experience. 

To  obtain  a  fine  copy  of  a  line  engraving,  in  which  the  hair¬ 
lines  are  to  be  faithfully  and  sharply  reproduced,  requires  a  good 
lens,  well  managed.  The  stop  must  be  very  small,  not  exceeding 
/  60,  or  one-sixtieth  of  the  focal  length.  The  lens  should  be  a 
large  one. 

Copying  is  the  most  delicate  and  difficult  branch  of  photo¬ 
graphy.  The  faint  light  admitted  by  the  small  stop  cannot  form 
a  brilliant  image;  the  attraction  to  the  developer  is  therefore 
’  weaker,  and  the  tendency  to  the  production  of  stains  is  greater, 
whilst  no  department  of  photography  requires  so  absolute  an 
absence  of  stains  as  this.  Consequently,  photographers  generally 
confine  themselves  to  the  central  parts  of  the  plate,  or  at  least 
leave  a  border  of  an  inch  or  more  around  the  image,  as  it  is  the 
borders  that  are  most  exposed  to  these  troubles. 


ON  COPYING. 


253 


The  bath  must  necessarily  be  in  good  order,  giving  clean, 
blooming  negatives.  The  developer  must  have  a  full,  though 
not  excessive,  dose  of  acetic  acid.  The  development  must  not 
be  prolonged,  but  be  rather  a  brief  one,  and  if  a  very  strong 
negative  be  wanted,  recourse  must  be  had  to  after-intensification. 

The  best  means  of  effecting  this  is  to  place  the  plate  in  a  solu¬ 
tion  of  corrosive  sublimate  until  it  becomes  entirely  white,  and 
then  to  flow  it  with  a  1-grain  solution  of  cyanide  of  potassium. 
The  cyanide  instantly  blackens  the  negative,  whilst  at  the  same 
time  it  clears  away  all  tendency  to  veiling,  if  any  existed. 

Another  excellent  method  is  to  chlorize  the  paper,  and  then  to 
apply  Schlippe’s  salt.  (For  details  of  both  methods  see  p.  173.) 

But,  for  the  most  part,  an  ordinary  development,  followed  if 
necessary  by  a  re-development,  after  fixing,  will  be  sufficient,  re¬ 
membering,  however,  that  neither  development  nor  re-develop¬ 
ment  should  be  pushed.  The  re-developing  liquid  should  be 
used  no  longer  than  it  is  quite  colorless,  instead  of  serving,  as 
in  other  work,  as  long  as  it  is  clear.  Heavy  deposits  of  silver, 
if  allowed,  will  evidently  clog  up  the  finer  lines. 

The  lens  to  be  used  must  be  free  from  distortion,  and  have  as 
flat  a  field  as  possible.  The  old  orthoscopic  lens,  now  rarely 
made,  copied  excellently.  The  view  lens  is  unsuitable.  Almost 
any  centrally  stopped  lens,  except  the  portrait  combination,  may 
be  used  with  success,  the  Zentmayer,  Steinheil  aplanatic,  Dali- 


Fig.  117. 


meyer  rapid  rectilinear,  Boss’s  doublet,  the  triplet,  from  any  of 
these,  if  a  good  specimen  of  its  class,  good  work  may  be  expected. 
As  the  focus  is  always  longer  in  proportion  as  the  size  of  the 


254 


PHOTOGRAPHIC  MANIPULATIONS. 


image  is  large  compared  with  the  object,  it  follows  that  for  copy¬ 
ing,  the  camera  will  often  need  to  be  lengthened  out,  and  this  is 
done  with  an  “  extending  cone.”  Fig.  117  represents  a  form 
devised  by  the  writer,  in  which  the  flap  C  is  hinged  on  to  the 
cone,  and  serves  to  support  and  steady  it.  The  cone  at  B  ex¬ 
tends  beyond  the  tube  of  the  lens,  so  as  to  form  a  sort  of  hood, 
excluding  extraneous  light.  Unless  means  are  taken  to  prevent 
extraneous  light  from  falling  on  the  lens,  brilliant  and  clear 
copies  cannot  be  obtained. 

Generally  speaking,  it  is  best  to  place  a  line  engraving  in 
fall  sunshine,  which  should  fall  on  it  in  a  direct  line,  and  not 
obliquely.  The  more  slanting  the  direction  of  the  sun’s  rays, 
the  more  conspicuously  will  the  grain  of  the  paper,  and  also 
other  irregularities,  be  rendered  in  the  negative.  By  using  direct 
sunshine,  it  becomes  possible  to  work  with  the  smallest  stop  fur¬ 
nished  with  lens,  thereby  reducing  the  astigmation  (p.  61)  to  a 
minimum,  and  so  to  obtain  the  hairlines  in  the  high  lights  of  the 
engraving,  accurately  reproduced. 

For  copying  Daguerreotypes ,  sunlight  reflected  by  a  mirror 
gives  excellent  results.  Photographs  may  be  copied  in  the  same 
way,  or  by  a  good  strong  out-door  diffuse  light.  They  do  not 
need  so  very  small  a  stop  as  line  engravings  do,  and  consequently 
not  so  brilliant  a  light. 

Mechanical  Appliances. — When  an  old  picture  is  to  be  copied, 
it  will  be  well  cleaned  and  then  hung  up  in  the  sunshine.  .(It 
seems  probable  that  an  application  of  glycerine  would  give  a 
clearness  and  brightness  that  would  materially  aid  in  copying. 
Afterwards  the  glycerine  could  be  easily  removed  with  a  wet 
sponge.)  Fix  the  camera  so  that  each  corner  of  the  picture  shall 
be  equally  distant  from  the  centre  of  the  front  lens,  and  take 
care  that  all  parts  of  the  picture  shall  be  equally  illuminated, 
also  that  the  direction  of  the  sunlight  shall  be  such  that  no  re¬ 
flections  shall  reach  the  lens. 

The  copying  of  engravings  and  smaller  pictures  may  be  done 
in  the  same  way.  But  it  is  more  convenient  to  make  a  special 
arrangement  as  follows  : — ■ 

A  square  piece  of  wood  of  convenient  size  is  placed  upright 
upon  a  long  narrow  table,  giving  the  piece  of  wood  the  same 
breadth  as  the  table.  At  the  sides  of  the  board  (see  Fig.  118) 
strips  two  or  three  inches  wide  are  fastened,  coming  some  inches 


THE  STEREOSCOPE. 


255 


below  the  table  top,  and  fitting  close  up  to  it.  These  act  as  guides, 
so  that  when  the  square  piece  of  wood  is  pushed  backwards  or 

Fig.  118. 


forwards,  it  always  retains  a  position  at  right  angles  to  the  long 
side  of  the  table.  Behind  another  narrow  strip  is  fastened,  to 
act  as  a  base  and  keep  the  board  vertical.  Diagonal  lines  are 
drawn  from  the  corners,  fixing  the  centre.  The  camera  is  raised 
on  blocks  until  the  middle  of  the  lens  is  opposite  the  intersection 
of  the  diagonals. 

If  now  we  place  any  object  to  be  copied  on  the  centre  of  the 
board,  which  the  diagonals  easily  enable  us  to  do,  we  have 
simply  to  move  the  board  backwards  and  forwards  until  the  size 
and  the  focus  are  obtained.  The  general  arrangement  secures 
what  is  always  essential  in  copying,  viz.,  that  the  object  to  be  copied 
shall  be  exactly  parallel  with  the  focussing  screen.  In  the  arrange¬ 
ment  here  described,  the  camera  is  always  kept  with  its  sides 
exactly  parallel  to  the  table,  then  the  board  being  at  right  angles 
with  the  side  of  the  table,  the  necessary  parallelism  is  insured. 

Plans  may  be  well  copied  by  simply  laying  them  on  sensitized 
paper  and  exposing.  This  gives  a  paper  negative,  which  is  to  be 
laid  on  other  sensitized  paper  and  exposed — if  the  resulting  posi¬ 
tive  is  not  strong  enough,  it  is  brought  up  by  development. 
Plans  of  several  feet  square,  made  for  the  Treasury  Department 
at  Washington,  are  thus  beautifully  multiplied  by  Mr.  Walker, 
the  photographer  of  the  department. 


256 


PHOTOGRAPHIC  MANIPULATIONS. 


CHAPTER  X. 

THE  STEREOSCOPE. 


Fig.  119. 


This  ingenious  invention  of  Prof.  Wheatstone  depends  upon 
the  fact  that  the  two  eyes  see  the  same  objects  differently  in  con¬ 
sequence  of  their  difference  of  position.  If  we  view  a  collection 
of  objects,  as,  for  instance,  trees  in  a  grove,  and  then  moving 
our  position  by  a  few  yards,  we  view  them  again,  their  relative 
positions  will  seem  changed.  A  smaller  change  produces  this 
in  a  lesser  degree,  and  even  the  space  between  the  eyes  cor¬ 
responds  to  a  change  of  aspect,  which,  small  as  it  is,  aids  greatly 
in  fixing  relative  positions.  This  will  be  better  exemplified  as 
follows : — 

Let  the  polygonal  figure  (Fig.  119)  be  viewed  by  the  eyes  E 
and  E'.  Its  distance  from  them  and  its  size  may  easily  be 
imagined  such  that  the  eye  E  will  see  the  five 
sides,  1,  2,  3,  4,  5 ;  whilst  E'  will  see  the  five  sides, 
2,  3,  4,  5,  6.  The  eye  has,  by  long  experience, 
learned  unconsciously  to  combine  these  two  por¬ 
tions  of  the  polygon,  and  to  understand  thereby 
that  it  is  a  solid  body,  and  not  a  mere  projection 
on  a  flat  plane. 

If  we  suppose,  instead  of  the  polygon  at  Fig. 
119,  that  we  look  at  a  pillar,  of  a  portion  of  which 
that  polygon  is  a  section,  the  mind  realizes  that 
it  is  a  solid  body  by  its  consciousness  that  the  one 
eye  sees  partly  round  it  on  the  one  side,  and  the 
other  upon  the  other  side. 

If  then,  whilst  viewing  any  scene,  we  close 
first  the  one  eye  and  then  the  other,  it  is  evident 
that  we  shall  see  slightly  different  scenes  with  the  respective  eyes, 
the  combination  of  which  two  scenes  gives  us  a  distincter  sense 
of  distances  and  positions,  than  what  would  result  from  observa¬ 
tion  by  either  eye  separately. 

Now,  if  we  place  two  lenses  in  positions  of  distance  corre¬ 
sponding  with  that  of  the  two  eyes,  each  will  be  capable  of  pro- 


E' 


MICROSCOPIC  PHOTOGRAPHY. 


257 


ducing  an  image  corresponding  with  those  seen  by  the  separate 
eyes.  And  if  these  pictures  be  placed  side  by  side  before  the 
eyes,  and  each  be  looked  at  by  one  eye  separately,  these  two 
images  may  be  combined  by  the  brain,  precisely  as  the  two  views 
seen  by  the  eyes  in  observing  a  landscape.  Such  pictures  are 
made  in  the  stereoscopic  camera ,  in  which,  however,  the  lenses  are 
placed  somewhat  farther  apart  than  the  distance  which  separates 
the  human  eyes,  it  having  been  found  by  experiment  that  the 
effect  so  obtained  is  more  striking  than  if  the  actual  distance 
between  the  eyes  were  maintained  with  the  lenses,  which  also  it 
would  not  be  easy  to  carry  out  in  practice. 

All  the  operations  with  the  stereoscopic  camera  are  precisely 
the  same  as  with  the  ordinary,  except  the  mounting  of  the  prints 
when  finished.  These  should  be  cut  with  care  to  a  convenient 
size,  keeping  the  centres  of  the  cut  prints  to  correspond  as  nearly 
as  possible  with  the  point  directly  opposite  the  centre  of  the  lens. 

In  pasting,  they  must  be  reversed,  that  is,  the  print  which  is 
on  the  right  hand  side  as  printed,  must  be  mounted  left.  It  has, 
however,  been  shown  that  this  may  be  avoided  by  cutting  the 
sensitized  paper  to  twice  the  length  of  the  negative,  and  folding 
its  ends  till  they  meet  at  the  centre. 

The  figure  represents  the  paper  loosely  folded.  B  and  C  are 
pressed  down  till  the  edges  E  Er  meet.  The  sensitive  side  of  the 
paper  is  outermost.  Apply  the  side 
B  0  to  the  negative;  a  print  is  taken. 

The  sheet  is  then  turned  round  and 
the  other  side  printed.  Cutting 
through  at  A,  and  opening  out,  B 
and  the  piece  behind  it  give  one 
print,  and  C  and  that  behind  it, 
another,  each  with  the  sides  cor¬ 
rectly  placed  for  mounting,  and  not  needing  to  be  reversed. 

A  pair  of  stereoscopic  views  may  be  obtained  with  a  single 
lens.  The  two  views  are  taken  separately,  and  the  camera  moved 
a  little  laterally  for  the  second  view. 

The  stereoscope,  which  for  some  time  enjoyed  an  almost  un¬ 
bounded  popularity,  has  latterly  been  much  less  prized.  Larger 
views,  from  half  size  to  10  x  12,  are  capable  of  so  much  more 
artistic  effect,  that  they  are  taking  the  place,  and  deservedly,  of 
the  stereoscopic  slides,  and  will,  no  doubt,  increasingly  in  future. 


258 


PHOTOGRAPHIC  MANIPULATIONS. 


CHAPTER  XI. 

MICROPHOTOGRAPHY  AND  MICROSCOPIC  PHOTOGRAPHY. 

The  first  of  these  processes  has  for  its  object  the  production  of 
extremely  small  images  of  objects  intended  to  be  viewed  by  the 
microscope.  The  second  is  the  impression  upon  a  collodion  film 
of  the  image  seen  in  the  microscope. 

§  1. — Microphotography. 

If  a  negative  be  placed  in  a  suitable  apparatus,  and  its  image, 
extremely  reduced  in  size,  be  thrown  by  a  very  short  focus  lens 
upon  a  sensitized  albumen  plate,  that  image  may  readily  be  de¬ 
veloped  by  appropriate  means,  and  a  sharp  fine  positive  image 
be  got,  which,  when  viewed  by  a  sufficient  magnifying  power, 
may  exhibit  satisfactory  detail  if  all  the  manipulations  have  been 
well  performed.  The  process  evidently  involves  no  real  difficulty, 
except  that  the  image  is  so  exceedingly  small  that  its  develop¬ 
ment  requires  to  be  followed  by  the  microscope. 

The  form  in  which  this  description  of  work  first  attracted  public 
attention  was  in  the  reproduction  of  objects  which,  by  magnify¬ 
ing,  were  made  to  exhibit  striking  details,  lettering,  for  example. 
A  monumental  tablet,  for  instance,  reduced  until  much  smaller 
than  a  pin’s  head,  when  placed  under  the  compound  microscope, 
showed  many  lines  of  lettering,  all  perfectly  distinct. 

Subsequently,  however,  M.  Dagron  gave  a  new  impetus  to  the 
matter  by  substituting  for  the  microscope  a  modified  Stanhope 
lens,  having  one  end  a  plane  surface,  to  which  the  microscopic 
print  was  attached  permanently  by  Canada  balsam.  These  lenses 
were  manufactured  out  of  glass  rods  at  an  infinitesimal  price,  and 
enormous  quantities  have  been  sold  in  Paris.  In  this  country 
they  have  attracted  but  little  attention. 

In  the  late  war  between  Germany  and  France,  immense  use 
was  made  of  microscopic  photographs,  by  sending  them  on  collo- 
dium  plates  with  the  aid  of  carrier  pigeons,  into  Paris. 


MICROSCOPIC  PHOTOGRAPHY. 


259 


§  2. — Microscopic  Photography. 

In  microscopic  photography  the  images  are  enlarged  greatly 
above  the  natural  size.  The  operation  differs  from  ordinary  en¬ 
larging,  both  in  its  object  and  method. 

In  ordinary  enlarging,  the  object  is  usually  to  reproduce  from 
a  small  negative  a  large  paper  picture,  though  we  also  may 
obtain  enlarged  negatives  on  glass.  But  in  microscopic  photo¬ 
graphy  the  object  is  to  get  negatives,  large  or  small,  of  micro¬ 
scopic  objects,  often  enormously  enlarged. 

Dr.  Woodward,  of  the  U.  S.  Army,  has  far  exceeded  all  other 
experimenters  in  this  direction,  whose  results  have  come  under 
the  writer’s  notice.  Amongst  other  interesting  specimens  re¬ 
ceived  from  him  are  images  of  test  plates  made  with  different 
kinds  of  light.  The  effects  obtained  with  sunlight  are  altogether 
inferior  to  those  yielded  by  the  artificial  lights,  and  of  these  the 
magnesium  light  and  the  electric  light  obtained  with  carbon 
points  gave  better  results  than  the  calcium  light ;  even  the  latter, 
however,  proved  itself  far  superior  to  sunlight,  the  inferiority  of 
which  last  could  hardly  have  been  anticipated  in  the  absence  of 
decisive  tests. 

A  powerful  beam  of  light,  from  any  of  these  sources,  is  thrown 
through  a  compound  microscope,  and  the  image  is  received  upon 
a  sensitized  collodion  film.  An  ordinary  nitrate  bath  was  used 
by  Dr.  Woodward,  with  the  author’s  collo-developer  (see  p.  164) 
and  an  after-intensification  with  Schlippe’s  salt,  or  with  mercury. 

By  these  methods  Dr.  Woodward  has  been  “enabled  to  pro¬ 
duce  pictures  of  the  utmost  sharpness,  and  perfectly  satisfactory 
in  every  other  respect,  with  powers  up  to  two  thousand  and  five 
hundred  diameters,  and  these  pictures  bear  a  further  enlargement 
of  from  six  to  eight  diameters  in  a  copying  camera.  W e  have 
thus  obtained  excellent  pictures  up  to  ten  thousand  diameters.” 

Ordinary  collodions  were  found  to  work  very  well.  For  great 
enlargements,  where  the  light  was  weak,  a  collodion  containing 
two  grains  of  bromide  of  magnesium  and  five  of  iodide  of  magne¬ 
sium  was  found  useful,  the  deliquescent  action  of  the  nitrate  of 
magnesium  formed  preventing  the  drying  of  the  film. 

With  the  very  highest  powers,  such  as  Powell  &  Lealand’s 
one-fiftieth  objective,  the  correction  of  the  objective  to  suit  the 
violet  light  was  found  to  be  so  small  as  to  be  practically  unim¬ 
portant.  But  with  one-eighth,  for  example,  it  was  found  to  be 


260 


PHOTOGRAPHIC  MANIPULATIONS. 


essential.  As  a  general  thing,  images  taken  with  the  one-eighth 
and  enlarged,  gave  results  as  good  as  those  obtained  directly  with 
the  one-fiftieth. 

Drs.  Woodward  and  Curtis  have  obtained  many  valuable  mi¬ 
croscopic  photographs  by  this  process,  which  is  exceedingly  well 
adapted  to  increase  our  knowledge  of  the  structures  of  animal 
and  vegetable  tissues.  The  writer  has  received  from  them  beau¬ 
tiful  enlargements  of  minute  bloodvessels  and  blood-corpuscles, 
etc.  One  of  their  most  successful  amplifications  has  been  that 
of  the  Pleurosigma  angulatum,  of  which  they  have  obtained  good 
photographic  prints  on  paper,  magnified  up  to  nineteen  thousand 
diameters. 


CHAPTEE  XII. 

DEVELOPMENT  ON  PAPER. 

§  1. — Positive  Development  on  Chloride  of  Silver. 

Development  on  paper  requires  to  be  differently  managed 
according  as  we  wish  to  obtain  positives  or  negatives.  These 
operations  will  be  considered  under  different  heads,  commencing 
with  positives. 

Positives  may  be  developed  on  paper  with  the  aid  of  either 
iodide,  bromide,  or  chloride  of  silver,  or  with  a  mixture  of  these 
substances.  From  his  own  trials,  the  writer  long  since  decided 
on  chloride  as  being  the  best,  and  the  process  published  by  him 
several  years  ago  has  been  largely  adopted  with  or  without  con¬ 
siderable  variations. 

If  paper  be  impregnated  with  chloride,  bromide,  or  iodide  of 
silver,  be  exposed  for  a  short  time  under  a  negative,  and  then  be 
thrown  into  a  saturated  solution  of  gallic  acid,  a  picture  will 
soon  be  developed,  which  will  go  on  increasing  in  strength,  and, 
when  satisfactory,  may  be  taken  out,  washed,  and  fixed.  Such 
was  the  original  idea  of  development,  which  we  owe  to  the  late 
Eev.  J.  B.  Eeade,  though  it  was  shortly  after  taken  up  and  per¬ 
fected  by  Mr.  Fox  Talbot,  to  whom,  by  many,  it  has  been  as¬ 
cribed.  Both  these  experimenters  operated  with  iodide  of  silver, 
and  turned  their  attention  rather  to  negative  development  than 
positive.  Some  years  later,  Blanquart  Evrard  took  the  process 
up,  used  a  mixture  of  bromide  and  iodide  of  silver,  fumed  with 
hydrochloric  acid,  and  toned  his  pictures  with  hyposulphite  and 


DEVELOPMENT  ON  PAPER. 


261 


gold.  His  results  were  magnificent,  and  for  a  while  it  was  as¬ 
serted  that  none  of  his  pictures  had  ever  been  known  to  fade. 
With  increasing  lapse  of  time,  however,  this  has  ceased  to  be 
true,  and  his  pictures  have  in  some  cases  faded. 

The  process  which  the  writer  brought  forward  was  based  upon 
the  use  of  lead  in  connection  with  gallic  acid.  It  had  been  known 
before  that  the  addition  of  acetate  of  lead  to  gallic  acid  greatly 
increased  its  powers  of  action,  but  as  a  precipitate  was  formed, 
rendering  the  liquid  muddy,  this  objection  interfered  with  the 
use  of  the  lead  salt,  and  the  fact  remained  without  application. 

Having  ascertained  that  gallate  of  lead,  the  precipitate  formed 
when  acetate  of  lead  was  added  to  gallic  acid,  was  soluble  in 
acetic  acid,  the  writer  applied  this  observation  to  development 
both  positive  and  negative,  and  with  excellent  results,  especially 
in  the  former  case.  The  economy  of  gallic  acid  was  enormous, 
the  rapidity  of  development  was  heightened,  and,  what  was  of 
far  more  consequence,  the  clearness  of  the  development  was 
greatly  enhanced,  so  that  of  all  kinds  of  development,  this  was 
the  safest  and  least  liable  to  accident.  The  course  was  so  regu¬ 
lar  and  uniform  that  many  prints  could  be  developed  at  once,  and 
the  bath  kept  in  working  order  for  a  longer  time  and  with  a 
greater  number  of  prints.  This  was  probably  because  the  large 
quantity  of  acetic  acid  used  restrained  the  precipitation  of  the 
silver,  whilst  the  action  of  the  lead  expedited  the  development. 

The  following  are  the  details  of  this  process. 

For  a  twenty-four  ounce  developing  bath,  dissolve  four  grains 
of  gallic  acid  in  a  few  ounces  of  water,  and  add  about  half  an 
ounce  of  a  solution  of  acetate  of  lead,  thirty  grains  to  the  ounce, 
of  which  a  stock  may  be  conveniently  kept  on  hand.  A  thick 
white  precipitate  falls.  Next  add  acetic  acid  till  this  precipitate 
redissolves — a  little  excess  of  acetic  acid  does  no  harm,  but  is 
rather  beneficial.  Filter  this  and  dilute  to  twenty  ounces.  To 
four  ounces  of  water  add  a  few  drops  of  solution  of  nitrate  of 
silver  from  the  positive  printing  bath,  and  mix  with  the  rest. 

These  various  operations  should  be  performed  a  short  time 
only  before  the  bath  is  wanted,  as  naturally  it  will  not  keep. 

The  development  may  be  effected  either  on  plain  or  on  albu- 
menized  paper.  It  is  commonly  believed,  universally  it  might 
be  said,  that  development  on  albumenized  paper  is  impossible, 
but  this  is  a  mistake.  The  treatment  of  the  paper  must  be  dif¬ 
ferent,  but  either  sort  will  develop  in  the  foregoing  bath. 

To  develop  on  plain  paper,  float  it  for  one  minute  upon  a  five- 


262 


PHOTOGRAPHIC  MANIPULATIONS. 


grain  solution  of  sal-ammoniac.  Sensitize  on  a  nitrate  bath  acidu¬ 
lated  with  tartaric  acid,  as  follows  : — 


Nitrate  of  silver 
Tartaric  acid 
Water 


I  ounce. 
26  grains. 
13  ounces. 


Good  results  can  be  obtained  with  half  this  strength,  but  for 
general  use  it  is  not  advisable  to  economize  the  silver  so  much. 
It  is  almost  superfluous  to  say  that  this  sensitizing,  and  the 
placing  in  and  taking  out  of  frames,  will  be  performed  in  a  room 
by  yellow  light,  and  not  as  in  the  preparation  of  ordinary  posi¬ 
tive  paper.  The  same  care  in  excluding  white  light  as  in  the 
wet  collodion  process  must  be  exercised. 

The  paper,  when  dry,  is  placed  under  a  negative  and  exposed 
to  light,  direct  sunlight  is  best,  for  from  fifteen  to  sixty  seconds, 
according  to  the  light,  the  season,  and  the  negative.  The  writer 
advises  to  continue  the  exposure  until  the  image  reaches  a  pale 
chocolate  color.  Some  stop  at  the  pale  violet.  Good  results  are 
got  either  way,  but  the  former  seems  preferable.  Of  course  the 
frame  must  not  be  opened  for  examination. 

It  is  a  mistake  to.  assert,  as  some  have  done,  that  no  details  are 
got  in  the  development  that  were  not  visible  faintly  in  the  print 
when  taken  from  the  frame.  On  the  contrary,  much  that  is  not 
any  way  visible,  comes  out  distinctly  in  the  development. 

In  fact,  the  writer  has  proved  this  capacity  of  chloride  to  yield 
details  in  development,  which  were  originally  invisible,  in  rather 
a  striking  manner.  A  piece  of  paper  sensitized  with  a  chloride 
only,  was  taken  and  placed  behind  a  negative,  and  a  single  mag¬ 
nesian  spiral  was  burned  at  a  little  distance.  On  removing  the 
paper  nothing  was  visible,  but  the  careful  application  of  a  de¬ 
veloper  brought  out  the  image  with  all  the  details,  in  a  surprising 
manner.  The  details  were  as  full  as  if  iodide  of  silver  had  been 
used,  but  the  picture  was  very  flat. 

When,  then,  the  print  is  judged  to  have  been  sufficiently  ex¬ 
posed,  it  is  removed  from  the  printing  frame,  and  plunged  evenly 
and  quickly  into  the  developing  bath.  With  the  bath-  above 
described,  the  development  requires  about  five  minutes  to  com¬ 
plete  it.  The  prints  should  generally  be  stronger  than  they  are 
intended  to  be  when  finished,  for  they  lose  in  the  fixing. 

As  soon  as  the  print  is  judged  to  be  sufficiently  developed,  it 
is  thrown  into  water  to  stop  the  action,  and  is  then  toned  with 
gold  precisely  in  the  same  way  as  with  any  other  positive  on 
paper.  If  not  toned,  it  will  have  an  unpleasant  coppery  color, 


DEVELOPMENT  ON  PAPER. 


263 


which  seems  almost  unavoidable  in  developed  prints.  The  writer 
has,  however,  obtained  a  pleasant  purple  tone  by  using  serum  of 
milk  (whey,  see  foot  of  p.  264)  in  the  salting  of  the  paper. 

It  will  be  seen  that  the  above  bath,  though  containing  only 
one-sixth  of  a  grain  of  gallic  acid  to  the  ounce,  acts  much  like 
an  ordinary  developing  bath,  made  twenty  times  stronger.  This 
shows  how  remarkable  is  the  agency  of  lead  in  increasing  the 
activity  of  gallic  development. 

For  albumenized  paper  a  larger  dose  of  tartaric  acid  is  ad¬ 


visable.  Take — 

Nitrate  of  silver . 1  ounce. 

Tartaric  acid . 36  grains. 

Water . 12  ounces. 


Float  on  this  ordinary  albumenized  paper  for  two  to  three 
minutes,  and  then  proceed  otherwise  as  before. 

Paper  prepared  in  this  way,  although  albumenized,  bears  de¬ 
velopment  very  well,  and  gives  good  results.  Not  so  good,  how¬ 
ever,  either  on  albumenized  or  plain,  as  with  sun-printing,  though 
sometimes  not  far  behind.  Still,  it  must  be  said  that  when  the 
sun’s  light  is  left  to  do  its  perfect  work,  that  work  is  better  and 
more  completely  done  than  when  we  break  it  off  just  commenced, 
and  force  our  solutions  to  complete  it.  It  would  seem  that  it 
could  not  be  otherwise.  There  is  less  depth  in  the  shadows  and 
less  brilliancy.  The  developed  print  is  apt  to  be  softer  than  the 
direct  sun  print,  and  shows  less  contrast ;  it  is  also  more  sunk  in, 
and  shows  the  grain  of  the  paper  more.  And,  although  the  de¬ 
velopment  can  be  effected  on  albumenized  paper,  it  is  more  diffi¬ 
cult  and  less  certain  than  on  plain. 

This  last  described  paper  has  good  keeping  properties.  If 
placed  in  a  tight  tin  case,  thoroughly  protected  from  light,  it 
shows  but  little  tendency  to  spontaneous  decomposition,  and  I 
have  succeeded  in  developing  a  perfectly  clean  picture,  after  an 
interval  of  at  least  ten  days  after  sensitizing. 

§  2. — Negative  Development  on  Paper.1 

Calotype  Process . — Float  paper  on  a  20-grain  plain  solution  of 
nitrate  of  silver,  and  then,  after  drying,  upon  a  25-grain  solution 

1  An  interesting  negative  process  on  paper,  by  Mr.  H.  J.  Newton,  will  be 
found  in  the  Philadelphia  Photographer ,  vol.  iv.  page  187.  The  writer  regrets 
that  space  will  not  allow  him  to  extract  it  in  full. 


264 


PHOTOGRAPHIC  MANIPULATIONS. 


of  iodide  of  potassium ;  on  the  first  solution  for  one  minute,  on 
the  second,  ten  minutes.  Dip  in  water  to  wash  off  the  excess  of 
iodide  and  dry.  In  this  condition  the  paper  keeps  well,  if  pro¬ 
tected  from  light. 

Make  now  6  ounces  of  cold  saturated  solution  of  gallic  acid, 
dissolve  800  grains  nitrate  of  silver  in  6  ounces  of  water,  mix  the 
two  and  add  an  ounce  of  strong  acetic  acid.  No  more  of  this 
sensitizer  should  be  made  than  is  needed,  as  it  will  not  keep  more 
than  a  few  hours.  Therefore,  in  sensitizing  a  few  sheets  it  is 
better  to  make  much  less  and  brush  over  the  paper  instead  of 
floating.  Whether  dipped  or  floated,  the  solution  is  left  on  but 
a  minute;  the  sheet  is  dipped  into  water,  the  excess  of  moisture 
blotted  off  with  bibulous  paper,  and  the  sheet  is  ready  for  use. 
A  very  brief  exposure  is  sufficient  to  form  an  image  which  will 
go  on  strengthening  in  the  dark,  or  may  be  hastened  by  washing 
over  with  the  sensitizing  mixture,  just  above  described,  and 
holding  to  the  fire. 

This  process  gave  excellent  results,  and  was  long  a  great 
favorite,  until  the  collodion  process  superseded  it.  The  negative 
so  obtained  may  be  paraffined  as  follows. 

Paraffining. — Take  a  fine  translucent  paraffine  candle — not  the 
paraffine  that  resembles  spermaceti,  but  the  very  translucent 
sort — and  scrape  it  down  to  shreds  with  a  knife  or  piece  of  broken 
glass.  Strew  some  of  these  on  a  piece  of  filtering  paper,  lay  the 
negative  upon  them,  put  more  shreds  on  the  negative,  then  another 
piece  of  filtering  paper,  and  iron  with  a  right  warm,  but  not  hot, 
flat-iron.  If  on  looking  at  the  negative  it  is  not  found  to  be 
moist  all  over,  put  more  shreds  on  the  dry  part,  and  repeat. 

Wax  Paper  Process. — Legray  showed  that  paper  might  be  first 
waxed,  and  that,  even  after  this,  it  would  take  up  sufficient  iodide 
of  potassium  if  immersed  in  the  solution,  to  admit  of  sensitizing 
on  solution  of  nitrate  of  silver  and  exposing  in  the  camera.  Serum 
of  milk,  or  whey,  was  found  useful  in  this  process,  and  the  writer 
has  used  it  with  good  effect  in  developing  positives.  After  wax¬ 
ing  good  photographic  paper  with  fine  bleached  wax,  soak  it  for 


an  hour  in — 

Serum  of  milk  .......  25  ounces. 

Milk  sugar . |  ounce. 

Bromide  of  potassium . 48  grains. 


Iodide  of  “ . 180  “ 

To  obtain  whey,  heat  the  milk  to  boiling,  add  a  very  few  drops 
of  acetic  acid  till  it  turns,  then  the  white  of  an  egg  to  clear,  and 


DEVELOPMENT  ON  PAPER. 


265 


filter  through  paper.  Milk  sugar  can  be  had  of  the  druggist. 
Dry  and  put  away  between  folds  of  paper.  Sensitize,  when 
wanted,  on  a  thirty-five  grain  solution  of  nitrate  of  silver  to 
which  glacial  acetic  acid  has  been  added  in  the  proportion  of  one 
ounce  of  acid  to  fourteen  of  bath.  Immerse  in  two  waters  suc¬ 
cessively,  dry  between  folds  of  blotting-paper.  Expose  in  the 
camera  either  between  two  pieces  of  plate  glass,  or  else  paste  the 
edges  of  the  paper  over  the  edges  of  a  piece  of  glass.  Develop 
with  a  saturated  solution  of  gallic  acid,  to  which  nitrate  of  silver 
has  been  added  in  the  proportion  of  one  grain  to  two  ounces  of 
gallic  acid  solution  and  a  little  acetic  acid.  Probably  the  lead 
developer,  already  described,  would  be  every  way  better.  (See 
section  1  of  this  chapter.) 

§  3. — Paper  Enlargements. 

Life-sized  portraits  may  evidently  be  obtained  in  the  same  way 
as  ordinary  portraits,  provided  we  proportionately  increase  the 
size  of  the  lens.  But  unfortunately  the  defects  of  lenses  increase 
with  their  size,  and  this  is  especially  true  with  respect  to  depth 
of  focus.  The  larger  the  lens,  therefore,  the  more  difficult  it  will 
be  to  get  different  parts  of  the  subject  simultaneously  in  focus, 
and  consequently,  while  it  is  by  no  means  impossible  to  take  life- 
sized  portraits  direct,  it  is  much  more  common  to  effect  this  object 
by  enlarging,  with  the  aid  of  a  solar  camera,  from  a  small  nega¬ 
tive,  generally  made  expressly  for  this  purpose  (see  p.  177). 

Enlargements ,  printed  by  the  solar  camera,  may  be  finished  in 
the  camera,  that  is,  the  whole  work  may  be  done  by  sun-printing, 
precisely  like  printing  in  a  frame.  But  the  method  of  develop¬ 
ment  is  also  practicable,  and  this  may  be  done  in  the  manner 
already  described,  by  chloride  development,  or,  at  the  option  of 
the  operator,  the  negative  process  on  bromo-iodized  paper  may 
be  used,  of  course  without  taking  means  to  render  the  paper 
transparent.  But  as  the  negative  process  is  specially  intended 
for  those  cases  where  the  illumination  is  very  weak,  as  in  the 
camera  obscura,  and  as  the  light  of  the  solar  camera  is  always 
abundant  for  chloride  development,  that  process  will  give  the 
most  satisfaction,  provided,  as  before  said,  that  the  operator  de¬ 
sires  to  develop,  and  not  to  finish  in  the  usual  way.  Also  when 
the  picture  has  been  supposed  to  be  finished,  and  has  been  found 
to  be  too  weak,  development  may  be  resorted  to  to  bring  it  up. 

18 


266 


PHOTOGRAPHIC  MANIPULATIONS. 


§  4. — The  Solar  Camera. 

The  apparatus  for  enlarging  from  a  small  negative  may  be 
arranged  in  several  different  methods ;  these  instruments  are 
known  as  solar  cameras. 

Woodward's  Camera. — In  this  instrument  the  solar  rays  are 
received  upon  a  mirror  of  silvered  (not  quicksilvered)  glass, 
whose  office  it  is  to  reflect  them  horizontally.  They  then  pass 
through  a  plain  convex  flint  glass  condenser  of  eight  inches  in 
diameter. 


Fig.  121. 


R  R  R,  parallel  rays  from  the  sun  falling  upon  the  mirror  M1 
which  reflects  them  horizontally  through  the  opening  in  the  wall 
WWof  an  apartment.  Inside  is  the  condenser  C  C)  which  con¬ 
verges  them  to  a  focus  F \  where  a  photographic  objective  is 
placed.  A  negative  A  being  interposed  between  the  condenser 
and  the  objective,  its  magnified  image  is  formed  on  the  screen. 
In  Woodward’s  apparatus  the  lens  at  F  is  an  ordinary  portrait 
objective. 

The  mirror  M  is  mounted  with  racks  and  pinions,  and  requires 
to  be  moved  every  few  seconds  to  keep  the  rays  horizontal. 

Van  Monckhoven' s  Camera. — The  objection  made  to  Woodward’s 
apparatus  has  been  that  the  condenser  was  not  large  (eight  inches 
diameter),  and  consequently  the  working  was  slow.  The  size 
could  not  be  increased  without  introducing  much  spherical  aber¬ 
ration  and  injuring  the  sharpness  of  the  image. 

To  avoid  this  evil,  Yan  Monckhoven  introduced  a  negative  lens 
behind  the  condenser,  a  thin  meniscus,  and  also  replaced  the  ob¬ 
jective  by  one  of  a  construction  devised  by  himself. 

Light  is  thrown  upon  the  apparatus  in  the  same  way  as  with 
Woodward’s.  Or  a  heliostat  may  be- very  advantageously  applied 
to  any  solar  camera.  In  this  instrument  the  mirror  is  regulated 


DEVELOPMENT  ON  PAPER. 


267 


by  clock-work,  so  that  it  moves  with  the  sun  and  takes  always 
such  an  angle  that  the  rays  reflected  by  it  fall  horizontally  upon 
the  condenser. 

Yery  good  work  has  been  executed  with  Yan  Monckhoven’s 
camera. 

Other  Solar  Cameras. — The  same  optical  principle  which  was 
adopted  by  Woodward,  has  been  made  the  basis  of  a  number  of 
different  arrangements,  by  Shive,  Roettger,  Fontayne,  Gales,  Car- 
butt,  and  others.  In  Shive’s,  Roettger’s,  Fontayne’s,  and  Carbutt’s 
the  direct  rays  of  the  sun  are  used  without  a  reflector.  The  dif¬ 
ference  in  these  instruments  depends  upon  the  mechanical  con¬ 
trivances  applied  to  carry  out  the  optical  arrangement.  In  all  a 
plano-convex  lens  is  placed  with  its  convex  side  to  the  light. 
Between  its  posterior  surface  and  its  focal  point  the  negative  is 
introduced.  At  its  focal  point  the  photographic  objective  is 
placed,  and  the  image  is  thrown  upon  a  screen  in  the  back  of  the 
camera.  Roettger  claims  for  his,  to  which  he  gives  the  name  of 
“parallactic,”  a  greater  facility  for  following  the  sun’s  path. 
The  most  recent  modification  is  Carbutt’s,  which  is  itself  a  modi¬ 
fication  of  Stuart’s ;  in  it  the  whole  tripod  moves.  The  base  of 
the  tripod  is  a  triangle,  moving  upon  a  hinge  at  one  corner. 
The  corner  falls  directly  under  the  condensing  lens ;  this  gives 
a  facility  for  making  a  great  angular  movement  in  a  very  little 
space.  The  apparatus  is  mounted  permanently  in  a  room  at  the 
top  of  the  house.  A  section  is  removed  from  the  south  end  of 
the  roof,  to  admit  the  direct  sunshine. 

It  will  be  seen  that  the  only  modification  of  the  optical  prin¬ 
ciples  of  Woodward’s  camera  which  has  been  made  is  that  of  Y. 
Monckhoven,  who  introduced  the  negative  meniscus  into  it,  to 
correct  the  spherical  aberration,  and  thereby  enable  him  to  use 
a  larger  condenser.  The  size  of  the  condenser  is  of  material  im¬ 
portance,  for  on  it  depends  the  intensity  of  the  image.  Wood¬ 
ward’s  condenser  was  eight  inches  in  diameter,  while  Y.  Monck¬ 
hoven  was  enabled  to  raise  his  to  twenty.  The  time  required 
for  printing  an  enlargement  of  a  given  size  with  the  two  would 
be  approximately  inversely  as  the  squares  of  the  diameters, 
namely,  as  400  to  64,  or  as  6  to  1,  or  thereabouts. 


268 


PHOTOGRAPHIC  MANIPULATIONS. 


§  5. — Printing  by  the  Solar  Camera. 

Little  special  need  be  said  on  this  head.  Albumenized  paper 
is  attached  to  the  screen,  and  the  image  gradually  appears,  re¬ 
quiring  a  time  which  may  extend  from  half  an  hour  to  many 
hours  to  reach  full  strength. 

This  slow  printing,  requiring,  as  it  does,  incessant  attention  to 
keep  the  apparatus  duly  placed  as  respects  the  sun,  unless  the 
operator  possesses  a  heliostat,  is  very  objectionable  and  annoying, 
and  therefore  leads  to  the  extensive  use  of  development  in  order 
to  shorten  the  time.  This  part  of  the  subject  has  been  already 
explained. 

Efforts  have  been  made  to  shorten  the  time  required  for  sun¬ 
printing.  That  of  M.  Yan  Monckhoven,  founded  upon  the  use 
of  nitroglucose ,  has  been  well  spoken  of,  but  does  not  seem  to  have 
passed  into  general  use.  The  nitroglucose  process  may  be  used 
either  for  direct  printing  or  for  enlargement. 

Nitroglucose  is  prepared  by  adding  one  part  of  pulverized 
sugar  to  one  of  sulphuric  acid  previously  mixed  with  one  of 
monohydrated  nitric  acid.  After  an  action  of  about  five  minutes, 
the  mass  is  to  be  removed  from  the  acid  and  washed  with  cold 
water.  This  crude  nitroglucose  is  to  be  purified  by  dissolving 
in  alcohol  and  precipitating  by  adding  water,  in  which  it  is  in¬ 
soluble. 

This  nitroglucose,  according  to  Dr.  Y.  Monckhoven,  does  not 
precipitate  nitrate  of  silver,  but  acquires  that  property  if  its  alco¬ 
holic  solution  is  kept  for  eight  or  ten  days  at  a  temperatue  of 
110°  F.  Its  application  is  as  follows :  the  paper  is  passed  through 
an  alcoholic  solution  ten  grains  to  the  ounce,  is  hung  up  to  dry, 
and  is  then  immersed  for  two  hours  in  an  ordinary  salting  solu¬ 
tion.  Next,  sensitized  on  a  twenty-five  grain  plain  solution  of 
nitrate  of  silver,  and  hung  up  to  dry.  So  prepared,  it  keeps  for 
many  months. 

In  use,  the  paper  is  exposed  in  the  solar  camera  for  about  a 
minute,  and  is  then  developed  with  gallic  acid  five  grains,  water 
ten  ounces,  glacial  acetic  acid  fifty  minims.  The  author  of  the 
process  claims  for  it  that  a  gallic  development  causes  albumenized 
prints  to  turn  yellow  in  the  whites,  whereas  with  the  nitroglucose 
process  the  whites  remain  perfect.  Now,  when  the  development 
on  albumenized  paper  is  carefully  conducted  on  the  principles 
laid  down  in  this  manual,  the  whites  do  not  turti  yellow.  More- 


SILVER  PRINTING. 


269 


over,  V.  Monckhoven  observes  that  the  operation  for  making  nitro- 
glucose  is  so  delicate  that  the  method  would  be  useless  were  it  not 
for  a  modification  discovered  by  him,  and  as  yet  unpublished. 

The  writer  has  himself  prepared  nitroglucose,  and  found  no 
difficulty  whatever  in  it.  He  has  found  it  advantageous  to  sub¬ 
stitute  fuming  sulphuric  acid  for  one-half  of  the  ordinary  acid. 
The  mixed  nitric  and  sulphuric  acids  must  be  allowed  to  cool 
thoroughly  in  a  covered  vessel  after  mixing,  powdered  white 
sugar  is  then  stirred  in,  enough  to  make  a  thin  paste.  Soon  a 
kind  of  grayish  dough  makes  its  appearance,  which  is  at  once 
removed  with  a  spatula  and  thrown  into  water.  This  is  con¬ 
tinued  till  the  dough  ceases  to  form,  when  a  little  more  sugar 
may  be  added,  though  its  yield  will  be  much  less  in  proportion 
than  that  of  the  first. 

The  nitroglucose  must  at  once  be  kneaded  up  with  water  to 
get  out  the  excess  of  acid  with  which  it  is  saturated,  and  which 
by  remaining  in  it  might  cause  its  decomposition.  For  completer 
purification,  the  nitroglucose  is  dissolved  in  alcohol  and  precipi¬ 
tated  by  water.  The  alcoholic  solution  should  be  poured  into 
water  (not  the  reverse),  with  constant  stirring.  The  nitroglucose 
separates  a  thin  dough,  which  is  to  be  washed  by  agitating  with 
several  waters,  and  then  should  be  kept  under  water. 


CHAPTER  XIII. 

SILVER  PRINTING. 

Elementary  directions  will  be  found  in  the  Introduction. 
Here  will  be  given  some  special  remarks  on  the  various  branches 
into  which  the  subject  divides  itself,  including  the  description  of 
a  new  and  hitherto  unpublished  method  of  sensitizing  paper  for 
positive  printing,  recently  devised  by  the  author,  and  which  has 
for  its  object  the  preparation  of  paper  which  can  be  kept  for  a 
long  time  after  silvering,  without  deterioration,  and  ready  for  use 
at  any  moment.  (See  sec.  6.) 

§  1. — Selection  of  Paper. 

The  paper  preferred  in  this  country  almost  universally  is  the 
Saxe  paper,  of  which  the  genuine  is  manufactured  by  Steinbach, 


270 


PHOTOGRAPHIC  MANIPULATIONS. 


and  of  which  there  are  many  imitations.  Some  of  Marion’s  paper 
is  also  sold  here,  often  as  “Saxe  paper,”  even  as  the  writer  has 
seen  done,  with  Marion’s  name  water-marked  on  the  edge.  “Rive” 
paper  is  little  known  here,  nor  Canson.  Whatman’s  paper,  much 
liked  in  England,  especially  for  negative  work,  scarcely  finds  its 
way  to  this  country. 

The  qualities  required  in  paper  are — to  be  made  of  good  stock 
— that  is,  fine  clean  rags ;  to  have  had  the  chlorine  used  for 
bleaching  thoroughly  removed,  as  also  the  antichlor  (generally 
hyposulphite  of  sodium).  Chlorine  left  in  the  paper  tends  to  in¬ 
jure  the  fibre,  but  is  otherwise  of  little  importance,  but  even  the 
slightest  traces  of  hyposulphite  make  ineffaceable  stains  and  dis¬ 
colorations.  A  print  thrown  by  mistake  into  hyposulphite  wash¬ 
ings,  turns  black  all  over,  the  hyposulphite  being  decomposed, 
and  sulphide  of  silver  formed  ;  of  course  a  similar  reaction  takes 
place  when  hyposulphite  is  left  in  the  paper — faint  traces  make 
brownish  spots,  visible  in  the  sensitized  paper  before  printing. 

Again,  the  paper  must  be  free  from  all  kinds  of  metallic  grains, 
which,  without  care,  are  liable  to  drop  into  the  pulp.  Metallic 
dust,  abraded  from  the  machinery,  forms  imperceptible  specks, 
which,  however,  reduce  the  silver  from  the  nitrate  bath,  and 
make  spots  in  the  print. 

In  this  country,  prints  are  almost  universally  made  upon  white 
paper,  but  rose,  purple,  and  other  tinted  papers  are  being  intro¬ 
duced,  and  serve  to  give  an  agreeable  variety. 

§  2. — Albumenizing  Paper. 

Few  operators  take  the  trouble  to  albumenize  their  own  paper. 
But  as  original  experimenters  require  to  understand  every  por¬ 
tion  of  the  process  of  photography,  and  as  it  may  happen  that 
photographers  may  desire  to  print  where  albumenized  paper 
cannot  be  got,  the  writer  gives  the  formula  which  he  has  used 
with  good  results. 

Take  the  whites  of  perfectly  fresh  eggs  and  add  thereto  liquid 
ammonia  in  the  proportion  of  five  drops  for  each  egg.  Measure 
the  quantity,  and  take  six  grains  of  sal  ammoniac  for  each  ounce 
of  albumen.  This  may  be  dissolved  in  an  ounce  of  water  for 
each  five  eggs,  or  if  very  high  albumenizing  is  desired,  it  may 
be  dissolved  in  the  smallest  possible  quantity  of  water. 

Add  the  sal  ammoniac  solution,  and  let  the  whole  be  beaten  up 


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271 


to  a  froth,  so  that  no  liquid  portion  be  left.  Set  away  for  twelve 
hours  or  more  (a  cool  damp  place  is  best),  and  pour  off  the  liquid 
portions  which  have  settled  out  of  the  froth.  These  are  per¬ 
fectly  clear  and  free  from  foreign  matter. 

The  albumen  thus  prepared  is  placed  in  a  flat  pan  and  the 
papers  rested  on  it  for  three  or  four  minutes,  and  then  lifted  off 
and  hung  up  to  dry.  The  faster  the  drying  the  higher  the  gloss, 
and  therefore  these  papers,  when  prepared  commercially,  are 
often  dried  in  rooms  kept  at  a  suffocating  heat. 

In  small  experiments,  the  albumen  may  with  a  little  dexteritv 
be  applied  with  a  broad  (two-inch  or  more)  camel’s-hair  brush. 
With  care,  streaks  may  be  avoided. 

Some  have  recommended  the  use  of  glacial  acetic  acid  (three 
drops  to  each  egg)  instead  of  the  ammonia.  Lyte  remarks  that 
this  tends  to  yellowness  in  the  whites  of  the  prints,  and  the 
author’s  experience  has  been  the  same. 

In  salting,  considerable  latitude  is  allowable.  Eight  or  ten 
grains  of  sal  ammoniac  is  about  an  average  quantity,  which  is 
sometimes  reduced  to  six,  sometimes  increased  to  twelve.  An 
absurd  secrecy  is  practised  by  many  makers  of  albumenized 
paper  as  to  their  salting,  and  this  introduces  some  uncertainty  as 
to  the  proper  treatment :  strong  salting  requires  a  stronger  bath, 
and  with  paper  of  which  the  salting  is  not  known,  some  trials 
may  be  requisite  to  determine  the  appropriate  bath. 

The  weaker  the  salting  the  less  is  the  exhaustion  of  the  posi¬ 
tive  printing  bath,  but  it  is  not  quite  sure  that  the  pictures  so 
produced  are  quite  as  permanent. 

In  the  preservation  of  albumenized  paper,  two  things  are  to  be 
borne  carefully  in  mind.  First,  that  if  the  paper  be  kept  in  a 
moist  atmosphere,  it  will  not  give  brilliant  prints.  This,  is  be¬ 
cause  the  salt  used  becomes  to  some  extent  dissolved  in  the 
hygroscopic  moisture  absorbed  by  the  paper,  and  is  drawn  by 
capillary  attraction  into  the  body  of  the  paper ;  thus  the  silvered 
surface  is  less  perfect.  This  is  more  the  case  with  common  salt, 
chloride  of  sodium,  and  less  with  chloride  of  barium,  than  with 
chloride  of  ammonium.  Common  salt  is  the  most  deliquescent, 
chloride  of  barium  the  least  soluble  of  the  three. 

On  the  other  hand,  excessive  dryness  is  to  be  avoided,  the  coat 
of  albumen  becomes  too  horny  and  not  sufficiently  permeable. 
Many  adopt  the  plan  of  keeping  the  stock  of  albumenized  paper 
in  a  thoroughly  dry  place,  but  take  out  what  will  be  wanted  for 


272 


PHOTOGRAPHIC  MANIPULATIONS. 


one  day’s  printing,  and  leave  it  twenty-four  hours  in  a  damp 
cellar,  in  order  that  it  may  take  the  nitrate  bath  more  evenly. 

Generally  speaking,  the  fresher  the  paper  the  better,  and  the 
less  chance  of  defects.  To  be  sure  of  obtaining  the  quality  of 
paper  desired,  it  is  best  to  purchase  directly  from  the  maker  or 
his  authorized  agent. 

Decomposed  albumen  is  always  hurtful.  If  it  be  kept  so  long 
before  applying  to  the  paper  as  to  acquire  a  bad  smell,  it  must 
be  rejected.  And  if  the  paper  be  kept  in  a  very  moist  place,  the 
albumen  may  putrefy  on  the  surface  of  the  paper. 


|  3. — Salting  Plain  Paper. 

In  salting  ordinary  paper,  the  most  various  proportions  of  salt 
have  been  recommended.  Two,  three,  or  four  grains  to  the  ounce 
are  about  a  recommendable  proportion,  and  give  good  results. 
A  little  gelatine  may  be  advantageously  introduced;  the  latter 
should  not  exceed  two  grains  to  the  ounce,  and  may  be  less.  It 
will  need  the  aid  of  heat  to  get  it  into  solution.  If  not  over 
one  grain  be  used,  the  liquid  will  scarcely  gelatinize  in  cooling. 


The  following  may  be  taken  : — 

Chloride  of  ammonium  ......  50  grains. 

Gelatine  .  .  .  . . 16  “ 

Water  . . 10  ounces. 


By  some,  chloride  of  barium  is  preferred.  The  greater  equiva¬ 
lent  weight  of  this  substance  requires  that  it  should  be  used  in 
larger  proportion.  As  follows  : — 

Chloride  of  barium  .......  200  grains. 

Gelatine . 45  “ 

Water . 30  ounces. 

A  difference  of  opinion  exists  as  to  the  proper  mode  of  prepa¬ 
ration.  High  authorities  recommend  that  the  paper  be  drawn 
through  the  solution.  But  as  it  is  the  invariable  object  to  keep 
the  materials  on  the  surface,  it  is  perhaps  better  to  float  the  paper 
for  a  few  moments  in  the  bath.  In  any  case,  it  is  desirable  that 
it  should  be  rapidly  dried,  before  the  solution  soaks  too  much  in. 

Arrowroot  paper  may  be  purchased  ready  salted.  The  effect 
of  the  arrowroot  is  to  keep  the  picture  more  on  the  surface,  and 
so  avoid  a  sunk-in,  mealy  effect.  If  warm  tones  are  wanted,  use 
the  benzoate  or  acetate  toning ;  if  black,  the  lime.  These  papers 


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273 


need  vigorous  printing,  and  should  not  (according  to  Liesegang) 
be  toned  in  a  fresh  toning  bath,  but  only  after  some  albumen 
prints  have  been  toned  in  it. 

Good  results  may  be  obtained  by  floating  albumen  paper  with 
the  albumen  side  up.  This  gives  the  print  a  good  deal  the  effect 
of  being  made  on  plain  paper  very  highly  finished.  There  is 
not  the  transparency  of  shadow  which  makes  the  peculiar  beauty 
of  the  albumen  print,  but  there  is  also  less  gloss  and  glitter. 

§  4. — Sensitizing. 

Since  the  first  edition  of  this  book  was  published,  faming  with 
ammonia  in  one  shape  or  other  has  come  into  general  use,  and 
with  this  change  the  practice  of  making  the  “  ammonio-nitrate 
bath”  has  comparatively  passed  out  of  use. 

When  paper  is  to  be  fumed,  it  is  not  very  important  whether 
the  sensitizing  bath  is  acid  or  alkaline,  because  the  faming 
always  renders  the  paper  alkaline,  either  beforehand,  as  when 
the  fuming  box  is  used,  or  daring  the  exposure,  or  when  famed 
pads  are  employed.  The  usual  strength  of  the  bath  is  now  50 
to  60  grains  of  nitrate  of  silver  to  the  ounce.  A  satisfactory 
bath  will  be : — 


Positive  Bath. 

Nitrate  of  silver . 3  ounces. 

Water . 24  “ 

The  usual  practice  is  to  make  this  bath  faintly  acid  with  nitric 
acid,  though  some  excellent  operators  make  it  slightly  alkaline 
with  ammonia. 

On  this  bath  the  albumenized  paper  is  to  be  floated  about  a 
minute — a  little  less  in  hot  weather,  a  little  more  in  cold. 

After  the  sheet  has  floated  for  a  proper  time,  it  is  to  be  pinned 
or  otherwise  fastened  up  to  dry.  Buff  shades  to  the  room,  if 
wide  enough  to  cover  the  window  jambs,  will  be  a  sufficient  pro¬ 
tection;  if  too  much  white  light  be  admitted,  the  high  lights  of 
the  prints  cannot  be  expected  to  be  satisfactory.  In  some 
establishments  a  table  is  provided  with  a  back  or  screen  towards 
the  left,  seven  or  eight  feet  square.  This  protection,  and  keeping 
the  sensitized  paper  and  prints  in  drawers,  is  found  sufficient, 
provided  that  the  table  is  near  a  wall,  so  that  but  little  diffuse 
light  can  pass  round  the  screen. 


274 


PHOTOGRAPHIC  MANIPULATIONS. 


Consumption  of  Nitrate  of  Silver. — Different  photographers  have 
calculated  the  amount  of  nitrate  of  silver  consumed  in  sensitizing 
an  albumenized  sheet  of  18  x  22,  and  have  varied  between  wide 
limits,  some  fixing  it  as  low  as  60  grains,  others  as  high  as  110 
or  over.  Seventy-five  to  eighty  grains  is  probably  about  the 
true  quantity  that  is  abstracted  from  the  silver  bath,  part  of 
which  is  subsequently  recovered  from  the  washings. 

Alum  in  the  Printing  Bath. — Mr.  H.  T.  Anthony  recommends 
the  addition  of  alum  to  the  bath;  about  2  grains  to  the  ounce  of 
bath  seems  to  be  the  right  proportion,  and  to  tend  to  keep  the 
bath  clean  and  free  from  discoloration.  By  this  means,  he  states, 
he  gets  as  good  results  from  a  85-grain  bath,  as  on  the  old  plan 
with  a  50-grain.  He  advises,  after  the  printing  is  done,  to  soak 
the  prints  in  water  acidulated  with  acetic  acid,  before  toning 
them. 

Blotting  Sensitized  Paper. — Some  very  successful  workers  blot 
all  their  paper,  to  obtain  equal  action  and  avoid  drops  of  bath 
solution  collecting  on  the  surface  in  drying.  Thick  blotting  pads 
are  provided,  rather  larger  than  the  sheets.  On  one  the  sensi¬ 
tized  sheet  is  laid  face  down  and  pressed,  then  another  pad  and 
another  sheet,  and  so  on.  The  pads  may  be  used  many  times 
over  before  they  become  too  much  charged  with  solution — finally 
they  are  burned  to  recover  the  silver.  The  abstraction  of  the 
silver  solution  does  not  reduce  the  vigor  of  the  prints,  which  are 
obtained  very  uniform  in  character  and  free  from  stains. 

If  the  paper  is  allowed  to  dry  between  the  pads,  it  will  be  apt 
to  turn  yellow.  It  is,  therefore,  best,  as  quickly  as  the  liquid  is 
completely  absorbed,  to  remove  the  sheets,  pin  them  up,  and  let 
them  dry. 

Management  of  Bath. — The  positive  bath  by  use  soon  turns 
yellow  and  loses  strength.  The  first  trouble  is  to  be  remedied 
by  shaking  up  with  half  an  ounce  to  an  ounce  of  kaolin,  accord¬ 
ing  to  the  size  of  the  bath.  The  strength  must  be  kept  steadily 
up  to  the  mark  originally  fixed,  and  this  is  either  done  by  watch¬ 
ing  carefully  the  character  of  the  prints,  and  adding  silver  liber¬ 
ally  as  soon  as  they  show  any  signs  of  deterioration,  or  by  means 
of  the  argentometer ,  a  sort  of  hydrometer  expressly  made  for  the 
photographer,  and  which,  by  sinking  more  and  more  deeply  into 
the  bath,  indicates  the  exhaustion  of  the  nitrate  of  silver.  With 
the  age  of  the  bath,  however,  its  indications  become  less  reliable, 


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275 


in  consequence  of  the  accumulation  of  other  nitrates  in  the 
bath. 

These,  however,  appear  to  some  small  extent  to  take  the  place 
of  nitrate  of  silver.  At  least,  Meicke’s  experiments  showed  that 
the  quantity  of  silver  abstracted  from  an  old  bath  was  less  than 
from  a  new  one,  sometimes  by  as  much  as  15  or  20  grains  to  the 
sheet,  and  it  seems  not  unreasonable  to  suppose  that  the  alkaline 
nitrates  gradually  accumulating  in  the  bath  had  something  to  do 
with  this.  A  sharp  controversy  was  carried  on  in  England  for 
some  space  of  time  over  the  question  of  the  utility  of  alkaline 
nitrates  in  the  bath.  Generally,  nitrate  of  soda  was  tried.  The 
bulk  of  the  rather  conflicting  evidence  seems  to  have  been  in 
favor  of  the  advantage  of  the  addition,  a  result  undoubtedly 
confirmed  by  Meicke’s  experiments  above  mentioned. 

§  5. — Washed  Sensitive  Paper. 

One  of  the  serious  annoyances  connected  with  photographic 
printing  lies  in  the  rapid  deterioration  of  the  paper,  which  quickly 
turns  yellow,  thus  destroying  the  brilliancy  of  the  white.  It  is 
rarely  safe  to  keep  the  paper  from  one  day  to  another,  especially 
in  hot  weather.  Two  bad  results  follow:  that  if  the  weather 
changes  from  fair  to  dark,  a  portion  of  the  paper  prepared  for 
the  day’s  use  is  apt  to  be  spoiled;  whilst,  on  the  other  hand,  it 
the  day  changes  from  dark  to  bright,  there  is  no  paper  ready  to 
profit  by  it. 

The  preparation  of  a  paper  with  good  keeping  qualities  has 
consequently  been  felt  to  be  an  object  of  the  greatest  importance. 
Such  paper  has  been  prepared  commercially  in  France;  its  mode 
of  manufacture,  however,  has  been  kept  absolutely  secret.  So 
far  the  only  published  method  of  obtaining  a  paper  that  can  be 
kept  is  the  Washed  Paper  Process,  here  to  be  explained.  This 
process,  however,  involves  a  considerable  amount  of  additional 
manipulation  in  the  washing  of  the  paper  after  sensitizing  it. 
The  writer  has  lately  taken  up  and  finished  some  investigations 
commenced  some  years  ago,  and  has  succeeded  in  finding  a  method 
free  from  this  objection,  and  requiring  no  more  labor  to  prepare 
than  the  ordinary  silvered  paper,  yet  sufficiently  permanent  to 
be  kept  for  a  considerable  length  of  time  without  deterioration. 
This  method  will  be  described  in  the  next  section  following. 


276 


PHOTOGRAPHIC  MANIPULATIONS. 


In  the  Washed  Paper  Process ,  the  paper,  as  soon  as  it  is 
removed  from  the  printing  bath,  is  thrown  into  water,  to  remove 
the  excess  of  nitrate  of  silver.  As  to  the  amount  of  washing  that 
the  paper  will  bear,  different  operators  have  reached  very  differ¬ 
ent  conclusions,  and  the  practice  has  not  been  so  generally 
adopted  as  to  have  led  to  the  accurate  fixing  of  these  conditions. 
Some  succeed  best  by  simply  drawing  the  paper  through  one 
water;  in  this  condition  it  approximates  more  nearly  to  ordinary 
silvered  paper.  Others  draw  it  through  two,  three,  or  even  four 
waters,  so  that  the  last  water  shall  show  no  clouding  by  reason 
of  chlorides  present  in  it,  thus  indicating  that  the  whole  of  the 
nitrate  is  washed  out.  When  thus  treated,  the  salting  must  not 
be  too  low,  and  the  silver  bath  must  be  kept  well  up  to  the  mark, 
strengthening,  from  time  to  time,  with  fresh  nitrate,  according  to 
the  number  of  sheets  sensitized.  The  amount  of  silver  abstracted 
will  depend  upon  the  salting,  but  for  average  paper  it  will  be 
fair  to  estimate  from  five  to  six  drachms  for  each  four  sheets  of 
paper  of  18  x  22.  After  what  number  of  sheets  the  strengthening 
will  be  required  will,  of  course,  depend  much  upon  the  quantity 
of  bath  used,  but  it  is  best  always  to  be  on  the  safe  side;  a  rule 
used  by  some  experienced  operators  is  to  strengthen  after  each 
five  sheets.  After  each  strengthening,  try  the  bath  with  test- 
paper,  to  make  sure  that  it  is  alkaline,  but  not  too  much  so.  If 
too  alkaline,  the  albumen  will  be  dissolved  off  the  surface  of  the 
paper.  If  the  strengthening  of  the  bath  be  neglected,  the  prints 
will  want  vigor. 

Paper  thoroughly  washed  has  been  kept,  according  to  M. 
Baden,  from  March  till  October,  without  deteriorating.  When 
it  is  intended  to  keep  the  paper  for  a  long  time,  much  more 
care  with  regard  to  light  must  be  exercised  through  the  opera¬ 
tions  of  sensitizing,  washing,  and  drying,  and  in  keeping  it  in  a 
dark  and  dry  place.  The  prints  themselves  cannot  be  kept  with 
the  same  safety  as  the  paper,  because  of  the  fuming  before 
printing,  but  they  may  lie  over  for  some  days  or  even  longer. 

An  advantage  in  using  several  waters  is  that  the  first  pan  can 
be  used  many  times,  until  its  contents  become  very  rich  in  silver, 
and  fit  to  evaporate  down  and  recover  the  silver  fit  for  use. 
Then  the  second  pan  receives  the  first,  and  so  on,  fresh  water 
taking  the  place  of  that  which  was  previously  the  last. 

The  washing  of  the  paper  after  sensitizing  does  not  take  the 


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277 


place  of  the  subsequent  washing,  but  the  prints,  after  they  come 
from  the  printing  frame,  must  be  again  washed  before  toning. 

Care  is  also  necessary  with  the  fuming,  which  may  easily  be 
carried  too  far.  Pad  fuming  (see  p.  279)  is  said  to  answer  best. 
If  the  prints  are  fumed  in  a  box,  and  are  left  in  too  long,  they 
will  tone  to  a  cold  blue.  It  is  said,  however,  that  this  over¬ 
fumed  paper,  by  keeping  for  a  day  or  two,  will  lose  some  of  its 
excess  of  ammonia,  and  give  better  tones.  Five  minutes  is  about 
the  right  time  to  leave  this  paper  in  the  fuming  box. 

The  high  salting  of  the  paper  above  spoken  of,  appears  to  be 
essential.  This  introduces  a  difficulty,  inasmuch  as  the  photo¬ 
grapher  rarety  prepares  or  knows  how  much  salting  is  contained 
in  the  paper  that  he  habitually  uses. 

It  will  be  easily  understood,  from  the  foregoing,  that  there  is 
more  or  less  uncertainty  connected  with  this  method.  Some 
have  obtained  very  satisfactory  results  with  it,  whilst  others 
have  been  disappointed  and  have  rejected  it.  This  uncertainty, 
and  the  considerable  additional  manipulation  required,  appear  to 
render  the  method  much  less  advantageous  than  the  following. 


§  6. — New  Method  of  Sensitizing  Paper. 

Some  years  ago  the  writer,  whilst  investigating  the  subject  of 
Paper  Development,  ascertained  that  by  the  addition  of  tartaric 
acid  to  the  sensitizing  bath  the  paper  could  be  kept  for  ten  days. 
As  paper  for  development  is  still  more  liable  to  deterioration 
than  that  prepared  for  positive  printing,  it  appeared  to  him  likely 
that  this  property  of  tartaric  (probably  also  of  citric)  acid  might 
be  made  the  foundation  of  a  new  printing  process  of  great  utility. 
Other  occupation,  however,  interfered  with  the  prosecution  of 
the  matter  till  recently,  when  the  experiment  was  tried,  and  with 
complete  success.  At  the  time  when  this  sheet  goes  to  press,  the 
writer  has  kept  this  new  paper  about  seven  weeks ,  at  the  expiration 
of  which  time  it  was  still  in  excellent  condition,  giving  brilliant 
prints  with  whites  just  as  perfect  as  when  freshly  made,  and 
toning  with  the  utmost  ease. 


Formula. 

Crystallized  nitrate  of  silver . 2  ounces. 

Tartaric  acid . 40  grains. 

Water . 16  ounces. 


278 


PHOTOGRAPHIC  MANIPULATIONS. 


The  nitrate  and  the  tartaric  acid  are  not  to  be  thrown  into  the 
water  together,  but  dissolved  in  separate  portions,  mixed,  let  to 
stand  some  hours,  and  then  filtered.  This  bath  is  then  used  and 
treated  precisely  like  an  ordinary  printing  bath,  except  that  it  is 
best  to  keep  it  out  of  the  light.  The  albumenized  paper  is  floated 
for  the  usual  time  and  hung  up  to  dry.  More  care  should  be 
taken  in  excluding  the  light  than  in  the  case  of  ordinary  silvered 
paper  intended  to  be  used  at  once,  and  when  the  paper  is  dry  it 
is  to  be  put  aside  in  a  close-fitting  box  and  kept  in  a  dark,  dry 
place  until  wanted  for  use. 

Sometimes  the  author  adds — 

Gelatine . 4  grains, 

Glycerine . 3  drops, 

to  each  ounce  of  the  bath.  The  gelatine  should  be  set  to  swell 
in  a  part  of  the  water,  and  then  be  dissolved  by  warming,  add 
the  glycerine  and  tartaric  acid  to  this,  and  pour  it  into  the  rest 
of  the  water  in  which  the  silver-nitrate  has  been  dissolved. 
Although  the  bath  now  contains  four  grains  of  gelatine  to  the 
ounce,  the  tartaric  acid  prevents  any  gelatinizing,  even  if  one 
employs,  as  the  writer  has  sometimes  done,  a  much  larger  pro¬ 
portion  of  gelatine.  It  also  filters  easily.  When  gelatine  is  used, 
the  prints  as  taken  from  the  frame  have  a  bright  brown  color ; 
they  tone  to  any  shade  desired  as  easily  as  the  others.  The 
use  of  gelatine  would  seem  to  tend  to  keep  the  print  more  on  the 
surface,  but  whether  there  is  any  real  benefit  in  it  is  scarcely 
certain.  Perfectly  satisfactory  prints  are  obtained  without  it. 
The  object  of  the  glycerine  is  to  remove  the  stiffness  which  the 
gelatine  tends  to  give  the  paper. 

The  fuming  is  done  shortly  before  using,  and  requires  no  par¬ 
ticular  care,  and  the  print  is  washed  and  toned  in  any  of  the  ordi¬ 
nary  methods.  The  writer  uses  the  acetate  toning  bath.  What  is 
rather  curious  is  that  while  the  albumen  side  of  the  paper  remains 
white,  the  back  often  acquires  by  keeping  a  brownish  coloration, 
which,  however,  disappears  entirely  in  the  toning  or  fixing,  and  no 
one,  in  examining  either  the  face  or.  the  back  of  the  print,  could 
distinguish  it  from  one  made  on  paper  just  dry  after  the  printing 
bath.  It  seems  possible  that  the  quantity  of  silver  in  the  bath 
might  be  reduced,  but  in  these  examinations  it  was  thought 
better  to  adhere  to  the  proportion  of  silver  actually  employed  by 
the  most  successful  workers  with  the  ordinary  bath. 


SILVER  PRINTING. 


279 


It  will  be  seen  from  tbe  foregoing  description  that  paper  with 
excellent  keeping  properties  is  as  easy  to  prepare  as  paper  that 
spoils  immediately.  It  is  only  adding  a  few  grains  of  tartaric 
acid  and  proceeding  otherwise  precisely  as  usual.  The  advan¬ 
tages  are  very  great  and  the  trouble  nothing.  The  method  will, 
the  author  trusts,  be  found  a  valuable  alleviation  to  the  troubles 
of  printing. 


§  7.— Fuming. 

A  convenient  and  close-fitting  wooden  or  tin  box  is  provided 
with  a  door,  and  either  pieces  of  cork  are  attached  to  the  sides 
near  the  top  inside,  or  else  cords  are  stretched  across.  To  these 
the  dry  sensitized  paper  is  attached  for  fuming.  This  operation 
lasts  for  ten  minutes,  and  is  best  performed  only  a  few  minutes 
before  printing.  If  the  fuming  be  too  much  prolonged,  the  print 
may  be  expected  to  be  flat  and  mealy,  and  to  be  severely  reduced 
in  the  fixing  bath.  On  the  other  hand,  an  irregular  spotty  effect 
indicates  insufficient  fuming. 

In  a  saucer  at  the  bottom  of  the  box  is  poured  some  strong 
liquid  ammonia.  The  quantity  is  not  very  important;  for  a 
small  box  and  a  dozen  or  twenty  quarter  sheets  of  paper,  an 
ounce  and  a  half  to  two  ounces  will  be  sufficient.  For  a  large 
box  and  twenty  or  thirty  whole  sheets,  two  dishes  with  two  or 
three  ounces  in  each  will  be  sufficient,  if  the  ammonia  be  good. 
(The  liquid  ammonia  of  commerce  is  very  variable  in  strength.) 
Carbonate  of  ammonium  has  been  recommended  by  Dr.  Liesegang 
as  an  advantageous  substitute  for  the  liquid ;  the  mode  of  ope¬ 
rating  is  precisely  the  same,  except  that  a  larger  quantity  is 
employed,  and  may  be  used  many  times. 

It  is  best  that  the  fumed  paper  should  be  exposed  to  the  air  for 
ten  or  fifteen  minutes,  to  allow  the  adhering  arnmoniacal  fumes  to 
pass  off,  before  laying  upon  the  negative. 

The  effect  of  fuming  is  to  give  rich,  brilliant  prints  with  ease 
and  certainty.  This  method,  now  in  very  general  use,  was  first 
proposed  by  Mr.  H.  T.  Anthony. 

Pad  Fuming. — Another  plan,  which  has  lately  been  a  good 
deal  used,  is  to  fume  pads  instead  of  the  sensitized  paper. 
These  pads  are  left  for  some  hours,  or  over  night,  in  the  fuming 
box,  and  are  placed  behind  the  silvered  paper  whilst  it  is  in  the 
printing  frame.  In  this  way  the  ammonia  acts  upon  the  silvered 


280 


PHOTOGRAPHIC  MANIPULATIONS. 


surface  during  the  operation  of  printing.  The  influence  of  this 
fuming  can  be  heightened  by  putting  pieces  of  oiled  silk  directly 
behind  the  fumed  pads,  in  order  to  prevent  all  escape  of  ammonia. 
Another  plan  has  been  recommended,  that  of  simply  rubbing  the 
pad  with  a  lump  of  carbonate  of  ammonia,  taking  care,  of  course, 
to  leave  no  grains  or  dust  on  the  pad. 

Fuming  with  a  pad  is  less  likely  to  injure  valuable  negatives 
than  fuming  the  paper  itself. 

§  8. — Printing. 

Before  placing  the  paper  in  the  frame,  it  is  necessary  to  be 
certain  that  it  is  perfectly  dry,  otherwise  the  negative  may  be 
injured;  a  careful  examination  should  be  made  of  every  part  of 
the  sheet  before  it  is  cut  to  pieces,  bearing  in  mind  that  a  single 
moist  spot  may  cost  a  valuable  negative.  The  paper,  especially 
if  albumenized  paper  be  in  use,  must  be  set  in  the  frame  neither 
roughly  nor  carelessly.  For  it  is  to  be  always  borne  in  mind 
that  a  negative  is  a  delicate  thing.  Even  the  best  varnish  is 
no  protection  against  rough  handling,  and  a  slight  scratch  may 
easily  occur  in  some  place  where  touching  out  may  be  either 
impossible  or  nearly  so.  The  paper  should  never  be  drawn  over 
the  plate,  especially  when  pressed  close  to  it.  It  must  be  laid 
flat  down  in  its  proper  position,  and  the  pads  laid  easily  and 
squarely  down  upon  it  and  secured  by  the  back. 

Printing  may  be  done  either  in  the  direct  rays  of  the  sun  or  in 
diffuse  light;  the  choice  between  the  two  will  depend  upon  the 
nature  of  the  negative,  and  the  preparation  of  the  paper  must  be 
regulated  accordingly. 

The  characteristic  of  printing  in  the  sun  is  softness,  of  printing 
in  the  shade,  strength  and  contrast.  Nevertheless,  prints  made 
in  sunshine  are  mostly  the  stronger,  simply  because  strong,  hard 
negatives  require  sun-printing.  And  so,  soft  prints  will  often  be 
found  to  have  been  executed  in  the  shade,  because  taken  from 
very  thin  negatives  which  could  not  be  made  to  }ueld  a  good 
print  in  any  other  way.  For  want  of  understanding  this,  very 
contradictory  and  erroneous  statements  have  often  been  published 
on  the  subject  of  sun  and  ‘shade  printing. 

A  photographer  will,  for  example,  start  out  with  the  intention 
of  printing  in  the  shade,  and  will  make  all  his  negatives  very 
thin  with  that  intention.  If  these  negatives  were  printed  in  the 


SILVER  PRINTING. 


281 


sun,  the  prints  would  be  utterly  worthless.  By  the  time  that  the 
shadows  were  deep  enough  to  stand  toning  and  fixing,  the  lights 
would  be  discolored  and  the  prints  spoiled.  To  examine  his 
prints  and  observe  his  mode  of  printing  might  lead  to  the  conclu¬ 
sion  that  shade-printing  gave  soft  prints,  whereas  the  fact  would 
be  that  the  thin  negative  gave  soft  prints  in  spite  of  the  mode  of 
printing.  • 

Another  will  prefer  bold,  vigorous  negatives,  and  will  develop 
and  redevelop  till  he  gets  them.  These,  if  printed  in  the  shade 
until  details  were  got  in  the  high  lights,  would  lose  all  transpa¬ 
rency  of  shadow,  which  would  be  converted  into  black  patches. 
The  exposures  would  be  tedious  and  the  prints  bad.  But  exposed 
to  a  bright  sun,  the  intense  rays  pierce  through  the  dense  parts 
of  the  negative,  and  give  us  the  details  in  the  lights  before  the 
shadows  are  overdone. 

Under  the  head  of  Salting,  it  has  already  been  remarked  that 
both  the  salting  and  the  nitrate  bath  must  be  regulated  so  as  to 
act  as  a  counterpoise  to  the  printing.  With  a  thin  negative  the 
bath  must  be  a  rich  one,  or  the  picture  will  tend  to  flatness.  A 
bold  negative  will  print  well  upon  a  less  highly  sensitized  paper. 
In  this  lies  the  explanation  of  the  much  discussion  over  strong 
and  weak  printing  baths,  some  succeeding  with  what  fails  with 
others,  all  depending  upon  the  nature  of  the  negative.  Again, 
when,  by  accident,  a  very  hard  negative  is  taken,  which  gives  a 
harsh  black  and  white  picture,  its  prints  may  be  improved  by 
using  an  extremely  weak  sensitizing  bath  (prolonging  the  floating 
of  the  sheet  upon  it  proportionally).  Extremely  hard  negatives, 
so  hard  as  to  be  unserviceable  in  any  other  way,  are  made  to 
yield  good  prints  by  washing  the  paper  after  sensitizing  it,  so  as 
to  remove  all  free  nitrate,  then  drying  and  exposing. 

Very  thin  negatives,  that  only  give  flat  prints  under  the  ordi¬ 
nary  treatment,  may  often  be  made  to  yield  excellent  prints  (pro¬ 
vided  they  are  not  actually  deficient  in  detail  in  the  shadows,  so 
that  they  are  wanting  in  density  only,  not  in  graduation  ;  the 
distinction  is  important)  by  printing  under  one  or  more  folds  of 
tissue-paper. 

It  will  easily  be  understood  that  where  negatives  are  printed 
in  large  quantities  for  sale,  they  are  likely  to  give  better  results, 
because  the  treatment  for  any  particular  negative,  in  respect  to 
salting,  sensitizing,  and  exposing,  can  be  well  made  out. 

The  proper  degree  of  salting  will  always  depend  upon  the 
19 


282 


PHOTOGRAPHIC  MANIPULATIONS. 


strength  of  the  sensitizing  bath,  and  correspond  with  it.  A  rich 
nitrate  bath  should  follow  high  salting,  and  the  reverse.  Where 
it  is  wanted  to  get  a  soft  print  from  a  very  hard  negative,  the 
salting  may  be  reduced  to  one  or  two  grains  per  ounce  of  water 
or  albumen,  to  be  followed4  by  a  weak  printing  bath  of  twenty  to 
thirty  grains  nitrate  of  silver. 

Another  remark  of  importance  is  this,  that  the  image  produced 
by  a  strong  light  stands  the  subsequent  operations  better  than 
that  produced  by  weaker  light.  A  print  made  in  direct  sunshine 
is  less  reduced  in  toning  and  fixing  than  one  made  in  the  shade. 
Consequently,  a  shade-print  requires  more  over-printing  in  the 
frame  than  a  sun-print.  The  sun-print  is  undoubtedly  the  stronger 
picture  of  the  two,  and  the  writer  holds  that,  other  things  being 
equal,  its  chance  of  permanence  is  greater  than  that  of  the  shade- 
print. 

The  lime  required  for  printing  will  of  course  vary  extremely; 
in  extreme  cases,  from  a  minute  or  two  to  many  hours.  The 
prints  are  to  be  examined  by  carrying  the  frame  to  a  dark  corner, 
loosening  one  end  of  the  back,  opening  it  and  observing  the  con¬ 
dition  of  the  print.  Particular  care  is  necessary  to  avoid  injuring 
the  negative  with  the  nail  in  lifting  back  the  print.  The  usual 
test  of  sufficient  printing  is  when  the  shadows  begin  to  bronze. 
At  this  time  the  highest  lights  should  be  either  still  quite  clear 
or  only  just  commencing  to  darken,  so  little  that  it  will  be  re¬ 
moved  in  the  subsequent  operations  and  the  white  left  pure.  If 
in  sun-printing  the  whites  begin  to  darken  before  the  shadows 
are  sufficiently  printed,  it  is  a  sign  that  the  negative  is  thin  and 
will  require  shade-printing.  If  in  shade-printing  the  shadows 
are  fully  printed  before  the  details  in  the  high  lights  are  got,  it 
is  an  indication  that  sun-printing  is  needed;  and  if  this  defect 
appears  in  sun-printing,  it  is  a  hint  that  the  negative  in  use  will 
require  paper  less  highly  silvered. 

Printing  on  Carbonate  of  Silver  has  been  introduced  in  France, 
and  has  acquired  considerable  popularity.  The  paper  is  first  sen¬ 
sitized  with  an  alkaline  carbonate,  and  then  silvered  on  a  plain 
silver  solution  (not  ammonio-nitrate).  Such  paper  keeps  long 
after  sensitizing,  but  requires  thorough  fuming  before  use,  and 
to  have  oiled  paper  or  oiled  silk  behind  the  back  of  the  paper 
whilst  printing,  to  retain  the  ammonia.  It  is  asserted  that  the 
prints  can  be  kept  a  month,  if  desired,  before  toning  and  fixing. 


283 


*4 


SILVER  PRINTING. 

Printing  under  Ground  Glass. — The  effect  produced  upon  the 
printing  of  a  negative  by  interposing  a  plate  of  ground  glass 
between  the  light  and  the  negative  is  undoubtedly  very  curious. 
A  great  softening  is  produced ;  negatives  which,  printed  in  the 
ordinary  way,  give  harsh  and  blocky  prints,  will  sometimes,  by 
this  treatment,  yield  excellent  results.  The  writer  has  seen  soft, 
beautiful,  and  delicate  prints  got  from  negatives  that  must  have 
been  rejected,  had  they  not  been  rendered  useful  by  the  applica¬ 
tion  of  this  ingenious  contrivance. 

It  is,  of  course,  chiefly  in  portraiture  that  this  device  is  useful. 
The  writer,  without  ever  having  used  it  himself  in  landscape 
printing,  has  seen  fine  prints  made  by  its  help  from  hard  nega¬ 
tives. 

Printing  under  ground  glass  has  somewhat  the  same  effect  as 
printing  under  tissue-paper  in  softening  the  image.  To  what  has 
already  been  said  under  the  head  of  “  Berlin  Portraits ”  (p.  194), 
it  may  be  here  added  that  some  vary  the  effect  by  coating  the 
ground  side  of  the  glass.  This  communicates  a  part  of  the  grain 
of  the  glass  to  the  print,  producing  somewhat  the  effect  of  an 
engraving. 

Mezzotint  Effects. — The  method  of  obtaining^  these  is  explained 
at  p.  194.  It  remains  to  mention  here  that  the  printing  should 
be  done  in  direct  sunshine,  and  that  it  is  found  that  the  best  re¬ 
sults  are  got  when  the  sun  shines  perpendicularly  on  the  negative. 
M.  de  Constant  suggests  driving  a  nail  perpendicularly  into  the 
face  of  the  printing  frame  ;  when  this  nail  casts  no  shadow ,  it  is  a 
proof  that  the  frame  is  perpendicular  to  the  sun’s  rays. 

Portraits  softened  in  these  ways  lose  the  harshness  so  con¬ 
spicuous  in  some  photographic  work.  They  show  less  definition 
and  boldness,  but  more  harmony  and  softness.  The  improve¬ 
ment  obtained  in  this  way  can  never  equal  that  resulting  from 
retouching  the  negative;  but,  where  this  is  not  practised,  it  may 
often  be  useful. 


§  9.— The  Pressure  Frame. 

The  construction  of  the  frame  is  of  too  great  an  importance  not 
to  receive  a  word  of  comment  here.  Two  very  serious  troubles 
arise  from  bad  pressure  frames,  breakage  of  negatives,  and  blurred 
prints.  Pressure  frames  generally  distribute  the  pressure  very 
badly. 


284 


PHOTOGRAPHIC  MANIPULATIONS. 


Take  an  ordinary  piece  of  glass,  the  size  of  the  frame,  lay  it  in, 
put  in  the  pads  you  commonly  employ ;  take  hold  of  the  frame 
in  both  hands,  the  fingers  on  the  back,  the  two  thumbs  resting 
on  the  glass  near  the  centre.  Press  forcibly  with  the  thumbs, 
until  the  glass  moves  back  a  little,  and  observe  the  amount  of 
resistance.  Next  bring  the  thumbs  up  to  one  end,  and  press 
there ;  you  will  probably  be  surprised  to  find  how  much  less  the 
resistance  is  there,  and,  consequently,  how  unequal  the  pressure. 

This  inequality  is  a  principal  cause  of  the  breakage  of  nega¬ 
tives  in  the  frames,  and  is  also  a  disadvantage  to  the  print;  for 
wherever  the  contact  is  not  good,  the  sharpness  of  the  print  will 
be  impaired,  and  this  more  so  with  shade-printing  than  printing 
in  direct  sunlight.  The  writer  has  already  expressed  his  prefer¬ 
ence  for  the  bar-frame,  Fig.  12,  p.  45. 

Many  operators  are  extremely  careless  as  to  what  padding  they 
use  between  the  back  of  the  frame  and  the  print,  considering  that 
anything  is  good  enough — mill-boards,  old  newspapers,  etc.  This 
is  quite  wrong;  such  inelastic  substances  cannot  give  good  con¬ 
tact,  and  always  endanger  the  negatives.  Moreover,  as  the  mate¬ 
rial  for  this  purpose  lasts  indefinitely,  it  is  worth  while  to  provide 
it  right,  once  for  all. 

The  one  thing  that  is  better  than  anything  else  is  piano-cloth. 
This  is  a  soft,  thick,  green  felt-cloth;  when  really  good,  it  is  about 
a  quarter  of  an  inch  thick.  It  is  expensive,  but  as  a  yard  will 
make  pads  for  twenty  whole  plate  frames,  the  cost  is  not  worthy 
of  consideration  when  the  safety  given  to  the  negatives  is  con* 
sidered.  A  single  thickness  is  sufficient,  and  a  fine,  elastic, 
equable  pressure  is  obtained,  which  is  invaluable.  If  by  long 
use  the  felt  has  become  flattened  down,  all  that  is  necessary  is  to 
slightly  wet  it  and  let  it  dry. 

The  next  best  substance  to  this  is  probably  a  good  thick  flannel 
— woollen  or  cotton;  the  former  is  the  more  elastic.  Whatever 
substance  is  used,  should  of  course  be  of  some  non-actinic  color. 

The  Registering  Pressure  Frame,  for  combination  printing,  has 
already  been  described.  See  Figs.  102  and  103,  p.  183. 

To  accomplish  the  printing  of  as  many  frames  as  possible  at 
once,  a  platform  is  set  up  outside  of  the  windows  and  on  the  level 
of  their  sills.  On  this  are  placed  slanting  blocks,  so  that,  when 
the  frames  rest  upon  them  in  rows,  each  frame  -will  be  inclined 
so  as  to  face  the  sunlight  as  much  as  possible.  At  different 
times  of  day  the  frames  are  differently  placed ;  when  the  sun  is 


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285 


low,  they  are  kept  more  nearly  perpendicular,  and  as  the  sun 
rises,  they  are  placed  more  level.  Much  time  is  saved  by  having 
the  frames  kept  well  facing  the  sun. 

A  southeast  exposure  is  the  most  desirable,  though  it  is  con¬ 
venient  to  have  at  least  one  window  with  a  westerly  exposure 
for  shade-printing.  Some  negatives  will  do  best  when  not  only 
printed  in  the  shade,  but  also  by  having  tissue-paper  interposed. 
It  is  therefore  convenient  to  have  some  frames  kept  permanently 
with  tissue-paper  stretched  across  the  borders. 


§  10. — Vignetting. 

When  the  print  softens  into  a  white  border,  it  is  called  a  vignette, 
and  this  mode  of  printing  offers  a  beautiful  variety.  The  nega¬ 
tive  is  usually  taken  in  precisely  the  same  way  as  for  ordinary 
printing,  and  the  difference  is  made  in  the  printing,  though  the 
effect  can  be  very  well  produced  once  for  all  in  the  negative,  if 
desi!*ed,  as  will  be  presently  explained. 

It  should  always  be  borne  in  mind  that  a  vignette  requires  a 
light  background.  A  sketchy  effect  (see  section  on  Backgrounds) 
is  very  pleasing  in  vignettes. 

Vignetting  with  a  Frame. — This  is  the  most  usual  way.  The 
negative  is  placed  in  a  frame  on  the  face  of  which  are  springs 
which  confine  blocks  of  wood ;  in  these  blocks  oval  holes  are 
cut,  widening  on  the  under  side  which  is  next  the  negative.  On 
the  upper  side,  farthest  from  the  negative,  tissue-paper  is  pasted 
to  soften  the  light. 

Yignetting  frames  are  also  made  expressly.  These  commonly 
have  pieces  of  tin  set  in  front,  provided  with  wire  rings,  over 
which  the  tissue-paper  is  to  be  pasted.  For  large  negatives  a 
convenient  vignetting  frame  may  be  made  by  tacking  a  piece  of 
stiff  pasteboard  upon  the  front  of  the  frame.  In  this  a  hole  is 
cut  of  the  size  desired,  and  this  hole  is  covered  with  tissue-paper. 

Vignetting  glasses  are  sold  in  which  a  deep  orange  enamel  is 
applied  to  the  border,  leaving  an  oval  space  in  the  middle,  of 
clear  glass ;  of  course  the  color  is  shaded  off  at  the  edges  of  the 
oval.  This  glass  is  to  be  placed  in  the  frame  between  the  nega¬ 
tive  and  the  light. 

Any  one  accustomed  to  photographic  manipulations  may  pre¬ 
pare  such  glasses  for  himself,  by  photography.  Cut  a  small  piece 


286 


PHOTOGRAPHIC  MANIPULATIONS. 


of  oval  hard  wood,  smaller  than  the  part  of  the  negative  that  is 
to  be  printed.  Prepare  a  eollodio-chloride  or  albumen  plate  for 
positive  printing,  lay  the  little  block  on  it,  and  expose  to  diffuse 
light,  turning  the  plate  now  and  then.  It  is  evident  that  the  part 
of  the  plate  that  is  covered  by  the  block  will  be  completely 
protected,  and  the  portions  round  it  will  be  shaded  off.  Or,  by 
reversing  the  operation,  and  using  a  hole  in  a  shield  instead  of  a 
block,  a  reverse  vignetting  plate  may  be  got,  that  is,  a  shaded 
centre  in  a  transparent  border.  This  may  be  used  as  a  negative 
from  which  any  number  of  vignetting  plates  may  be  prepared, 
either  by  contact  printing  or  by  development.  The  writer  can¬ 
not  recommend  this  as  being  a  very  easy  method,  but  it  is  per¬ 
fectly  practicable,  as  he  knows  from  having  devised  it  and  used 
it  several  years  since.  More  lately,  it  has  been  proposed  and 
advocated  by  others  in  print. 

Vignetting  with  Cotton. — A  piece  of  stiff  mill-board  is  tacked  to 
the  front  of  the  frame,  in  which  an  opening  is  cut  considerably 
larger  than  the  size  of  the  portion  of  the  negative  which  it  is 
intended  to  print.  White  cotton-wool  is  pressed  under  the  mill- 
board,  and  allowed  to  project  beyond  it  until  only  that  part  of 
the  negative  is  exposed  which  it  is  intended  to  print. 

Vignetting  with  Paper. — In  this  case  and  in  that  immediately 
foregoing,  the  part  of  the  negative  that  is  to  be  printed  is  exposed 
uncovered.  A  piece  of  thin  tissue-paper  is  cut  with  an  opening 

the  size  of  the  part  of  the  nega¬ 
tive  that  is  to  be  fully  printed ; 
then  another  piece  with  the 
opening  a  little  larger,  and  so 
on  for  a  considerable  number. 
These  are  pasted  together  and 
form  a  graduated  shield,  acting 
somewhat  like  the  vignetting 
glass  already  described.  By 
fastening  this  paper  shield  on 
the  glass  side  of  the  negative 
and  printing  in  the  shade,  the 
lines  of  the  successive  layers  of 
paper  can  be  concealed. 

The  sketch  in  the  margin  is 
taken  from  Mr.  Blanchard,  as 
showing  a  set  of  elegant  and  ap- 


Fig.  122. 


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287 


propriate  curves  suitable  for  card  size  (the  size  of  the  cut  is 
necessarily  smaller  than  that  of  a  card  portrait,  but  the  curves 
are  preserved  of  full  size).  Models  of  each  of  the  diminishing 
openings  are  to  be  cut  into  card-board  or  thin  tin;  these  once 
provided,  any  number  of  tissue  vignettes  may  be  made  from 
them  by  using  them  to  guide  the  point  of  the  penknife  in  cutting 
the  tissue-paper.  The  same  photographer  recommends,  for  other 
and  more  irregular  shapes  of  vignettes,  to  attach  to  the  back  of 
the  negative  a  piece  of  tracing  paper,  to  run  round  lightly  with 
the  pencil  the  portion  that  is  to  print  full  tint,  and  again  outside 
that,  the  portion  to  be  quite  white.  This  last  is  rendered  opaque 
with  any  red  or  black  color,  and  the  space  between  the  two  lines 
where  the  softening  is  to  be  is  graduated  by  rubbing  in  color 
with  a  common  artists’  stump. 

Vignetting  with  a  Lens. — This  ingenious  method  is  practised  by 
some  professional  photographers  to  the  exclusion  of  all  others, 
and  has  the  advantage  of  great  rapidity.  A  burning-glass  of  some 
size  (four  to  six  inches  in  diameter)  is  set  in  a  wide  frame,  or  a 
piece  of  thin  board.  The  negative  is  placed  with  silvered  paper 
behind  it  in  an  ordinary  frame,  and  the  concentrated  sunlight 
through  the  lens  is  allowed  to  fall  upon  the  face.  The  lens  is 
kept  moving  with  a  little  circular  motion,  confining  the  light  to 
the  parts  intended  to  be  printed.  In  from  ten  seconds  to  half  a 
minute  the  printing  is  finished.  As  the  heat  as  well  as  the  light 
is  concentrated  by  the  lens,  it  is  necessary  to  have  a  thin  piece  of 
plate  glass  in  the  frame  between  the  negative  and  sunlight,  to 
prevent  injury  to  the  negative. 

All  these  methods  give  excellent  results.  The  last  is  evidently 
applicable  chiefly  to  small  heads,  but  the  writer  has  seen  beau¬ 
tiful  vignetted  cards  made  by  it. 

We  next  come  to  vignetting  on  the  negative. 

Vignetting  by  Development. — When  the  dark  slide  comes  from 
the  camera,  the  back  is  opened  and  an  opaque  shaded  object  of 
the  shape  and  size  of  the  vignette  desired  is  laid  on  the  back  of 
the  plate,  which  then,  and  without  removing  from  the  slide,  is 
exposed  for  a  few  seconds  to  weak  diffuse  light.  When  the 
image  is  developed,  of  course  all  parts  of  the  plate  not  protected 
by  the  opaque  screen  just  described  are  developed  black,  in  con¬ 
sequence  of  the  second  exposure.  As  the  image  is  invisible  at 
the  time  the  opaque  screen  is  applied,  this  last  must  of  course 


288 


PHOTOGRAPHIC  MANIPULATIONS. 


have  been  arranged  in  such  a  way  by  the  image,  as  seen  in  the 
camera,  as  to  make  sure  of  the  screen  being  correctly  applied. 

Vignetting  by  a  Screen — Another  method  has  been  proposed. 
A  large  white  screen  is  to  be  prepared  with  an  oval  opening. 
This  screen  is  to  be  placed  between  the  camera  and  the  sitter,  who 
is  thus  seen  through  the  oval  opening.  The  screen  being  white, 
reproduces  itself  by  opacity  on  the  negative,  and  being  so  much 
nearer  to  the  lens  than  the  sitter  as  to  be  completely  out  of  focus, 
it  of  course  has  an  indistinct  shaded  border.  There  seems  an 
objection  to  this  plan,  that  it  tends  to  throw  so  much  white  light 
into  the  lens.  It  has  also  been  proposed,  instead  of  a  large  stand¬ 
ing  screen,  as  just  explained,  to  have  a  small  one,  only  a  few 
inches  from  the  lens,  and  attached  to  the  camera  itself,  capable 
also  of  being  regulated  in  distance  and  position. 

These  last  methods  are  rather  exceptional ;  the  use  of  the 
tissue-paper  fastened  over  openings  in  wooden  blocks  or  on 
metal  rings,  as  above  described,  is  almost  universal. 


§  11. — Toning. 

After  the  prints  are  removed  from  the  frame,  they  may  either 
be  thrown  directly  into  water  or  may  first  be  trimmed ;  the  latter 
method  is  found  preferable  by  those  who  operate  on  a  large  scale. 

The  prints  are  washed  by  placing  them  one  by  one  in  a  pan 
of  water,  where  they  all  lie  for  a  short  time.  This  water  is  to  be 
repeatedly  changed,  and  of  course  is  to  be  saved,  at  least  the  two 
or  three  first  washings.  It  is  rich  in  silver,  which  is  to  be  thrown 
down  as  chloride  by  common  salt.  A  neglect  to  wash  the  prints 
sufficiently  is  liable  to  produce  two  evils,  a  yellowing  of  the 
whites  in  the  toning  bath  and  a  difficulty  in  toning ;  these 
troubles  may  come  separately  or  together.  This  is  the  case 
especially  with  the  toning  baths  now  commonly  in  use.  Those 
toning  baths  into  the  composition  of  which  sulphocyanide  of 
ammonium  or  hyposulphite  of  sodium  enters,  do  not  present 
this  difficulty,  and  although  it  is  best  to  wash  the  prints  before 
toning  in  them,-  it  is  not  absolutely  necessary,  nor  need  it  be  so 
carefully  done. 

The  principle  of  toning  is  the  substitution  of  gold  for  silver  in 
the  print.  If  a  washed  print  be  simply  thrown  into  a  dilute  solu¬ 
tion  of  chloride  of  gold,  it  will  tone,  but  the  acidity  of  the  solu¬ 
tion  will  lead  to  a  great  reduction  in  the  strength  of  the  picture. 


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289 


It  is,  therefore,  needful  in  some  way  to  neutralize  the  acidity, 
which  may  be  done  with  carbonate  of  sodium,  carbonate  of  cal¬ 
cium,  or  certain  salts  that  have  an  alkaline  reaction,  such  as 
phosphate  of  sodium,  acetate  of  sodium,  or  borate  of  sodium, 
each  of  which  substances  forms  the  foundation  of  various  toning 
formulae.  The  explanation  of  their  action  is  this :  part  of  the 
alkali  present  becomes  converted  into  chloride,  which  enters 
into  combination  with  the  chloride  of  gold,  forming,  for  ex¬ 
ample,  in  the  case  of  soda,  chloraurate  of  sodium.  The  acid  pre¬ 
viously  in  combination  with  the  alkali  is  set  free,  but  being  in 
all  the  above  cases  a  weak  acid  (carbonic,  phosphoric,  acetic, 
boracic),  is  without  injurious  influence  on  the  bath.  In  fact,  other 
combinations  of  alkali  with  weak  acids  may  be  substituted.  The 
writer  has  obtained  excellent  results  with  benzoate  of  potassium , 
which  he  some  time  since  proposed  for  making  the  toning  bath 
with,  and  which  has  been  very  favorably  reported  on  by  others. 
Tungstate  of  sodium  has  also  been  used  with  good  effect.  Certain 
acids  have  a  reducing  effect  upon  salts  of  gold;  oxalates  and 
formiates  cannot  be  used  for  this  reason.  Citrate  of  sodium  has 
been  used  and  was  highly  recommended  some  years  back,  but  is 
now  little  employed. 

VARIOUS  TONING  FORMULAE. 

Alkaline  Carbonate  Toning  Bath. — To  make  this  very  popular 
bath,  the  gold  solution  is  simply  rendered  alkaline  with  bicar¬ 
bonate  of  sodium ;  the  following  proportions  may  be  used  : — 

Water . 32  ounces. 

Chloride  of  gold . 1  to  3  grains. 

Bicarbonate  of  sodium . 5  grains. 

Mix  twenty -four  hours  before  using. 

The  gold  gradually  tends  to  precipitate  from  this  bath,  whereby 
it  becomes  inactive.  Some  operators,  after  using,  add  just  enough 
hydrochloric  acid  to  make  it  turn  litmus-paper  red,  and  then, 
before  using  again,  add  enough  bicarbonate  of  sodium  to  cause  it 
to  turn  red  litmus-paper  blue.  In  this  way  it  keeps  indefinitely. 

Calcio-chloride  Toning  Bath. — A  solution  of  chloride  of  gold  is 
made,  one  grain  to  each  ounce  of  water,  and  a  couple  of  grains 
of  precipitated  chalk  to  each  ounce  are  added  and  shaken ;  next 
day  it  is  ready  for  use,  diluting  each  ounce  with  ten  to  twenty  of 
water. 


290 


PHOTOGRAPHIC  MANIPULATIONS. 


This  bath  tones  much  like  the  preceding ;  gives  brown,  purple, 
black,  or  black  tones,  and,  bj  overtoning,  blue.  Succeeds  best 
with  paper  sensitized  on  neutral  baths. 

Acetate  of  Sodium  Toning  Baths. 

Chloride  of  gold . 10  grains. 

Water . 80  ounces. 

Acetate  of  sodium . 1  ounce. 

This  bath  differs  considerably  from  the  foregoing.  It  will  not 
give  black  tones,  no  matter  how  prolonged  its  action,  but  gives 
splendid  warm  purple  shades  that  cannot  be  excelled  and  cannot 
be  equalled  by  the  common  carbonate  of  sodium  bath.  If  wanted 
for  use  in  the  shortest  time,  it  should  be  mixed  with  warm  water 
and  let  to  stand. 


Benzoate  Toning  Bath. 

Bicarbonate  of  sodium . 5  grains. 

Benzoic  acid  .  .  .  .  .  .  .  10  “ 

Chloride  of  gold . 1  grain. 

Water . 10  ounces. 

Gives  warm  tones  similar  to  the  preceding.  This  bath,  origi¬ 


nally  proposed  by  myself,  works  satisfactorily  and  keeps  very 
well.  It  acts,  perhaps,  a  little  more  uniformly  than  the  preceding. 
Instead  of  the  benzoic  acid  and  bicarb,  sodium,  an  alkaline  ben¬ 
zoate  may  be  employed. 

Although  any  of  these,  or  of  the  following,  can  be  used  for 
almost  any  purpose,  yet  certain  baths  will  always  have  uses  for 
which  they  are  specially  adapted.  Landscapes  should  be  toned 
only  with  the  acetato  or  the  benzoate  bath.  Small  heads,  as,  for 
example,  card  portraits,  are  best  toned  with  the  carbonate  bath. 
Eeproductions  of  engravings,  needing  a  pure  black,  may  be  toned 
with  the  carbonate,  but  still  better  with  the  chloride  of  lime  bath, 
to  be  presently  described. 

The  following  special  formulae  have  been  adopted  and  published 
by  experienced  and  successful  photographers — 

Mr.  Notman's  Formula. 

Water . 210  ounces. 

Acetate  of  sodium . 1  ounce. 

Bicarbonate  of  sodium . £  “ 

Nitrate  of  uranium . 16  grains. 

Chloride  of  gold  .  .  .  .  .  .  .  12  “ 


SILVER  PRINTING. 


291 


Keep  twenty-four  hours  before  using.  When  about  to  use, 
add  eight  grains  more  gold,  and  continue  to  add  according  to  the 
quantity  of  prints  toned.1 

Dr.  Shepard's  Formula. 


Chloride  of  gold . 4  grains. 

Water . 1  ounce. 

Neutralize  with  powdered  chalk. 

Chloride  of  lime . 4  grains. 


Let  stand  a  few  hours ;  pour  the  whole,  including  sediment, 
into  twenty  ounces  water ;  shake  well ;  let  stand  over  night,  and 
pour  off  the  clear  part. 

After  use,  return  to  bottle,  shake  up,  add  gold  in  proportion 
to  prints  toned,  and  a  grain  of  chloride  of  lime  for  every  grain 
of  chloride  of  gold,  or  thereabouts,  keeping  the  bath  smelling 
faintly  but  distinctly  of  chlorine.2 

This  bath  gives  a  variety  of  good  shades,  up  to  full  black.  In 
fact,  a  pure  black  seems  to  be  obtained  more  easily  with  a  chlo¬ 
ride  of  litne  bath  like  this,  than  with  the  other  formulae.  The 
bath  keeps  in  order  for  many  months,  always  ready  for  use. 


Dr.  Liesegang's  Formula. 


A.  Water . 50  ounces. 

Fused  acetate  of  sodium . 1  ounce. 

Phosphate  of  sodium . 45  grains. 

Chloride  of  lime . 15  “ 

B.  Water . 50  ounces. 

Chloride  of  gold  and  potassium  .  .  .  .15  grains. 


These  two  solutions  are  to  be  kept  separate  and  mixed  in  equal 
bulks  as  wanted,  immediately  before  use. 

It  seems  useless  to  farther  multiply  formulae,  but  it  may  be 
remarked  here  that,  as  the  function  of  the  substance  added  to  the 
gold  solution  is  to  neutralize  it,  and  prevent  the  corrosive  action 
of  the  chloride  of  gold  in  its  primitive  state,  it  follows  that  alka¬ 
lies  combined  with  almost  any  weak  acid  are  likely  to  give  good 
toning  baths,  of  which  an  almost  endless  variety  may  be  com¬ 
posed,  differing  considerably  in  the  tones  which  they  impart. 
In  addition  to  the  baths  given  here,  alkaline  tungstates  and  borates 
are  occasionally  used  and  liked  by  operators.  Those  who  desire 
to  experiment  can  take  the  second  formula  and  substitute  for  the 
acetate  of  sodium  such  other  salts  as  they  may  like  to  test. 


Pkilada.  Phot.,  III.  252. 


a  Ibid.,  II.  109. 


292 


PHOTOGRAPHIC  MANIPULATIONS. 


Slow  toning  gives  the  richest  and  finest  effects.  The  work 
may  he  expedited  by  heating  or  by  using  stronger  baths,  but  the 
results  are  not  so  fine.  When  a  bath  refuses  to  tone,  a  little 
more  chloride  of  gold  may  be  added  to  start  the  action. 


§  12. — Toning  and  Fixing  Baths. 

It  remains  to  speak  of  certain  baths  which  effect  at  once  the 
toning  and  fixing.  These  are  made  either  with  hyposulphite  of 
sodium  or  sulphocyanide  of  ammonium. 

Hyposulphite  Fixing  and  Toning  Bath. — If  two  ounces  of  hypo¬ 
sulphite  of  sodium  be  dissolved  in  eight  ounces  of  hot  water,  a 
grain  of  chloride  of  gold  previously  neutralized  with  carbonate  of 
sodium  (ammonia  or  phosphate  of  sodium  will  not  answer)  be  added 
after  the  hyposulphite  has  dissolved  and  been  stirred  up ,  we  obtain 
a  mixture  which,  after  half  an  hour’s  standing,  is  in  condition  to 
fix  a  print,  at  the  same  time  toning  it  to  a  rich  purple  black. 

Great  fault  has  been  found  with  this  mode  of  toning,  and  it 
is  certainly  less  safe  than  the  foregoing.  If  used  a  few  hours 
after  mixing,  and  if  a  very  moderate  number  of  prints  be  fixed  in 
it,  they  are  as  permanent  as  those  treated  separately.  But,  after 
standing,  or  if  more  than  a  very  moderate  number  of  prints  be 
fixed  in  it,  these  are  sulphur-toned,  and  speedily  fade  and  turn 
yellow. 

Good  tones  are  more  easily  got  by  separate  toning  than  by  this 
bath,  which  often  gives  coppery  tones  when  it  is  difficult  to  find 
a  reason  why. 

Sulphocyanide  Toning  and  Fixing  Bath. — The  writer  believes 
that  he  was  the  first  to  show  that  a  toning  and  fixing  bath  could 
be  made  with  a  sulphocyanide  and  chloride  of  gold.  His  experi¬ 
ments  were  made  in  1865,  and  are  referred  to  in  the  British 
Journal  for  1866,  p.  460  and  p.  508.  A  solution  of  sulphocyanide 
of  ammonium  mixed  with  chloride  of  gold  is  quite  free  from  the 
objection  of  fading.  But  the  prints  must  be  left  some  time  in  a 
second  and  fresh  bath  of  sulphocyanide,  otherwise  a  silver  com¬ 
pound  remains  in  the  paper,  and  eventually  darkens. 

To  prepare  this  bath,  chloride  of  gold  is  to  be  precipitated  with 
a  very  few  drops  of  ammonia,  and  redissolved  with  sulphocyanide 
of  ammonium.  This  rose-colored  solution,  if  used  fresh,  stains 
the  lights  rose-color.  But  if  kept  twenty-four  hours,  it  becomes 
colorless,  and  then  no  longer  stains  the  lights.  Dr.  Liesegang 


SILVER  PRINTING. 


293 


finds  the  addition  of  a  little  sal  ammoniac  very  advantageous  for 
preserving  the  whites  clear. 

When  toning  baths  lose  their  toning  properties,  there  frequently 
remains  gold  in  them  which  has  passed  to  an  inactive  state. 
This  can  be  thrown  down  by  making  the  bath  acid  with  a  little 
hydrochloric  acid,  and  then  adding  a  few  drops  of  solution  of 
sulphate  of  iron.  The  gold  falls  immediately  as  a  brown  powder, 
which  may  be  collected  on  a  filter  and  preserved. 

§  13. — Fixing  the  Prints. 

After  the  toning  is  finished,  the  print  is  passed  through  clean 
(but  not  necessarily  distilled)  water,  and  is  thrown  into  the  fixing 
bath. 


Hyposulphite  of  sodium .  1  pound. 

Water . 4  to  5  quarts. 


Using  it  a  little  stronger  in  winter  than  in  summer.  A  print 
ought  to  be  completely  freed  in  ten  to  twenty  minutes.  Too  long 
a  time  in  the  fixing  bath  will  diminish  its  beauty. 

Until  lately,  the  substance  exclusively  used  for  fixing  positives 
on  paper  has  been  hyposulphite  of  sodium.  Within  a  year  or 
two  sulphocyanide  of  ammonium  has  been  proposed  as  a  substi¬ 
tute,  on  the  ground  that  the  prints  were  thereby  secured  from  the 
injurious  action  of  partly  used  hyposulphite,  which  causes  fading. 

When  either  chloride  or  nitrate  of  silver  is  added  to  a  solu¬ 
tion  of  hyposulphite  of  sodium,  decomposition  takes  place,  with 
formation  of  tetrathionate  of  sodium,1  an  unstable  substance 
which  readily  undergoes  farther  decomposition.  Tetrathionate 
of  sodium  will  itself  tone  a  print  very  beautifully,  entirely  with¬ 
out  the  aid  of  gold;  its  toning  action  seems  to  depend  upon  the 
formation  of  sulphide  of  silver,  an  intensely  black  substance,  so 
that  this  process  may  be  likened  to  some  extent  to  the  blackening 
of  a  collodion  picture  with  alkaline  sulphide,  with  this  difference, 
that  the  action  of  alkaline  sulphide  is  far  more  powerful  and 
extends  to  chloride  and  iodide  of  silver,  which  it  blackens  readily 
and  intensely.  Tetrathionate  of  sodium,  or  rather  the  hyposul¬ 
phite  bath  containing  this  substance,  will  not  do  this,  nor  will  it 

1  Tetrathionic  acid  (S405)  differs  from  hyposulpliurous  acid  (S202)  in  haying 
one-fiftli  less  oxygen. 


294 


PHOTOGKAPHIC  MANIPULATIONS, 


attack  the  albuminate  of  silver  which  remains  to  some  extent  all 
through  the  substance  of  the  picture.  A  sulphur  toning  bath 
spares,  therefore,  the  whites  of  the  albumen  print,  which  a  solu¬ 
tion  of  alkaline  sulphide  would  turn  brown. 

The  tendency  to  fade  seems  to  be  distinct  from  this  production 
of  sulphide,  although  it  mostly  accompanies  it.  The  mere  pro¬ 
duction  of  sulphide  of  silver  could  not  cause  fading,  for  sulphide 
of  silver  is  a  very  permanent  substance.  This  we  see  abundantly 
proved  in  the  case  of  negatives  which  have  been  treated  first  with 
solution  of  iodine  and  then  with  a  bath  of  sulphide  of  potassium, 
and  which  have  no  disposition  to  fade,  even  by  long  keeping. 
The  addition  of  three  or  four  grains  of  bicarbonate  of  sodium  to 
the  ounce  of  fixing  bath,  is  useful  as  checking  somewhat  the 
tendency  to  produce  unstable  prints. 

Generally  speaking,  the  print  tends  to  gain  in  permanence  by 
a  prolongation  of  the  action  ;  some  which  the  writer  left  for  over 
an  hour  in  a  joint  toning  and  fixing  bath  exhibited  remarkable 
resistance  to  the  destructive  agencies  of  various  tests  which  he 
applied  to  them.  But  the  loss  of  brightness  by  long  immersion 
indisposes  photographers  to  permit  it. 

No  more  important  ddvice  can  be  given  to  the  photographer 
than  Do  not  spare  the  hyposulphite.  Even  a  fresh  bath  should  not 
be  used  for  too  many  prints,  and  a  bath  which  has  stood  over 
night  after  using,  should  be  unhesitatingly  rejected,  because  the 
decomposition  goes  steadily  on,  and  such  a  bath  is  in  much'worse 
condition  the  next  day  than  it  was  at  the  end  of  the  day  of  use. 

It  is  always  difficult  to  induce  photographers  to  act  upon  cor¬ 
rect  principle  as  respects  the  toning  bath,  not  merely  on  account 
of  the  expense  of  the  gold  solution  (it  requires  a  better  toned 
print  to  withstand  the  action  of  the  fixing  bath  when  the  latter 
is  fresh  and  in  right  condition  for  the  permanency  of  the  print), 
but  because  it  is  easier  to  work  with  a  decomposed  fixing  bath; 
so  much  so,  that  ten  years  ago  it  was  even  recommended  to  start 
decomposition  in  the  bath  by  substances  purposely  added.  But 
the  photographer  who  really  desires  to  do  justice  to  his  work 
will  not  allow  himself  to  be  swayed  by  such  considerations,  and 
may  be  assured  that  with  a  little  care  he  will  obtain  admirable 
tones  that  will  resist  the  fresh  hyposulphite  and  give  prints  that 
will  not  disgrace  him  by  turning  yellow  and  fading  out. 


SILVER  PRINTING. 


295 


§  14. — Washing. 

The  subject  of  washing  is  one  that  demands  the  greatest  care 
on  the  part  of  the  photographer,  and  there  is  an  almost  positive 
certainty  that  unless  it  be  done  systematically  and  thoroughly, 
the  prints,  however  carefully  managed  in  other  respects,  will 
rapidly  fade.  To  work  thoroughly,  the  water  must  be  used 
abundantly,  and  must  be  continually  changed. 

If  prints  be  thrown  into  a  tank,  and  a  stream  of  running  water 
be  made  to  flow  into  it  for  several  hours,  a  few  prints  may  be 
satisfactorily  washed.  But  if  the  number  be  large,  they  will 
interfere  with  each  other,  and  the  washing  will  be  more  or  less 
imperfect. 

The  simplest  contrivance  for  obviating  this  difficulty  is  to  have 
a  plug  in  the  bottom  of  the  tank  which  can  be  removed  from 
time  to  time  and  the  tank  emptied.  Both  the  time  of  washing 
and  the  quantity  of  water  necessary  are  in  this  way  very  much 
diminished,  but  care  is  necessary  that  the  prints  be  not  drawn 
into  the  orifice. 

To  obviate  the  necessity  of  attending  to  the  washing  and  re¬ 
moving  and  replacing  the  plug,  a  siphon  may  be  adapted  to  the 
tank,  which  will  come  into  ope¬ 
ration  as  soon  as  the  water 
reaches  a  given  height  (see  Fig. 

123).  The  siphon  pipe  passes 
under  and  through  the  bottom. 

The  opening  in  the  bottom  which 
communicates  with  this  pipe  is 
to  be  covered  with  a  strainer. 

Or,  what  is  much  better  still,  is 
a  plan  adopted  by  the  writer : 
a  ledge  is  made  all  round  the 
sides  at  a  height  about  an  inch 
above  the  bottom,  and  on  this 
rests  a  sheet  of  metal  pierced 
with  a  great  many  holes  about 
a  quarter  of  an  inch  in  diameter, 
away,  rest  on  this  plate  and  get  a  very  thorough  draining  away 
of  the  wash-water.  There  is  an  additional  advantage  in  this 
arrangement,  that  it  is  impossible  for  prints  to  lie  over  and  block 


Fig.  123. 


The  prints,  as  the  water  drains 


296 


PHOTOGRAPHIC  MANIPULATIONS. 


up  the  exit  pipe.  The  sheet  should  he  made  of  sheet  tin,  var¬ 
nished,  and  not  of  zinc. 

Considerable  care  must  be  taken  in  the  arrangement  of  the 
siphon  to  make  it  do  its  work  regularly.  To  empty  the  tank,  the 
water  must  of  course  run  out  faster  than  it  is  supplied ;  the  dia¬ 
meter  of  the  siphon  must  therefore  be  larger  than  that  of  the 
supply  pipe,  especially  as  the  water  comes  from  the  street  mains 
under  a  stronger  pressure  than  it  runs  off,  and  therefore  it  is  sup¬ 
plied  faster  than  the  mere  proportion  between  the  pipes.  This 
larger  size  of  the  siphon  introduces  this  difficulty,  that  the  water 
tends  simply  to  drain  off  through  it,  instead  of  starting  the  action 
of  the  siphon  and  so  emptying  the  tank.  This  difficulty  the 
writer  finds  may  be  lessened  by  lengthening  the  lower  limb  of 
the  siphon,  and  contracting  it  a  little  at  the  opening  of  the  lower 
end. 

The  stream  of  water  should,  in  all  cases,  be  thrown  obliquely 
against  the  side  of  the  tank ;  this  gives  a  rotary  motion  to  the 
whole  body  of  water  and  keeps  the  prints  constantly  moving,  a 
most  important  consideration,  and  which  should  never  be  neg¬ 
lected.  The  flow  of  water  through  the  siphon  will  be  regulated 
as  to  rapidity  by  the  difference  between  the  length  of  its  legs. 
The  greater  length  given  to  the  long  leg  the  more  rapid  the  flow 
of  the  water,  and  the  less  danger  of  draining  off  without  starting 
the  siphon. 

Other  and  more  complicated  plans  for  supplying  the  water 
have  been  proposed,  such  as  carrying  a  pipe  round  the  inside 
top  edge,  and  piercing  it  with  holes,  so  as  to  sprinkle  the  surface 
of  the  water  with  small  jets.  But  unless  these  are  so  contrived 
as  to  send  slanting  streams,  and  so  keep  up  a  rotary  motion,  a 
great  advantage  is  lost. 

An  ingenious  arrangement  consists  in  dividing  the  tank  into 
two  parts  by  a  compartment,  underneath  which,  and  under  the 
bottom  of  the  box,  is  placed  a  fulcrum  on  which  the  tank  balances 
backward  and  forward  with  a  see-saw  motion.  The  compartment 
that  is  uppermost  receives  the  stream  of  water  till  it  reaches  a 
certain  height ;  it  then  rocks  over,  and  the  other  side  receives 
the  water.  Meantime  the  first  side  is  emptying  out,  and,  when 
empty,  rises  again  and  again  fills.  In  a  narrow  compartment  or 
drawer  under  the  tank,  and  attached  to  it,  a  quantity  of  bullets 
are  placed  loose.  These  roll  from  end  to  end,  and  by  their 
weight  prevent  the  end  that  is  lowest  from  rising  too  soon. 


SILVER  PRINTING. 


297 


In  whatever  way  the  photographer  elects  to  wash  his  prints, 
he  must  satisfy  himself  that  the  work  is  done  effectually.  The 
mortification  which  must  be  experienced  by  those  who  have  dis¬ 
tributed  handsome-looking  prints,  at  finding  them  turn  yellow 
and  fade,  cannot  be  otherwise  than  very  great,  and  nothing  has 
acted  upon  photography  so  unfavorably  as  the  universally  recog¬ 
nized  uncertainty  as  to  the  durability  of  its  most  attractive  pro¬ 
ductions. 

There  are  several  ways  of  testing  whether  hyposulphite  is  com¬ 
pletely  washed  out.  Two  simple  but  not  very  accurate  methods 
are  the  following  : — 

1.  Touch  the  white  of  the  print  with  a  little  weak  solution  of 
nitrate  of  silver.  If  a  brownish  mark  is  made,  it  is  certain  that 
the  print  is  very  imperfectly  washed. 

2.  Touch  the  white  of  the  print  with  a  little  very  dilute  solution 
of  iodine  in  alcohol.  A  blue  mark  indicates  that  the  print  is 
pretty  nearly  free  from  hyposulphite.  Before  using  this  test,  it 
should  be  ascertained  that  the  particular  paper  used  is  sized  with, 
starch,  or  at  least  has  some  starch  in  the  sizing,  which  strikes  a 
blue  tint  with  iodine  when  no  hyposulphite  is  present.  To  fix 
this  point,  touch  a  piece  of  the  paper  that  has  not  been  sensitized 
with  a  little  very  weak  solution  of  iodine  in  alcohol,  on  the  back. 
If  no  blue  stain  is  produced  there  is  no  starch  in  the  sizing,  and 
this  test  cannot  be  used. 

3.  By  far  the  best  test  is  the  following :  Take  a  clean  beaker, 
or  even  a  two-ounce  vial,  provide  a  small  piece  of  white  blotting- 
paper,  on  which  make  some  irregular  marks  with  a  glass  rod 
dipped  in  weak  solution  of  acetate  of  lead. 

Fill  the  beaker  or  vial  nearly  full  of  water,  add  a  few  drops 
of  sulphuric  acid,  and  mix.  Then  put  in  a  part  of  the  print  to 
be  tested,  several  square  inches  at  least,  and  drop  in  ten  or  twenty 
grains  of  granulated  zinc,  and  immediately  cover  the  mouth  with 
the  blotting-paper  marked  with  acetate  of  lead,  which  must  be 
still  moist.  Leave  the  whole  for  ten  or  twenty  minutes.  If  the 
markings  turn  brown,  it  is  a  proof  of  insufficient  washing.  Prints 
that  will  stand  this  test  may  be  considered  as  thoroughly  washed, 
which  cannot  be  said  of  (1)  and  (2),  which  are  less  exact. 

It  is  necessary  to  be  sure  of  the  purity  of  the  sulphuric  acid  and 
zinc  employed,  and  the  best  way  to  accomplish  this  is  to  try  the 
experiment  d  blanc ,  that  is,  go  through  it  without  the  print  to  be 
tested.  If  then  the  markings  become  brown,  it  is  a  proof  that 
20 


298 


PHOTOGRAPHIC  MANIPULATIONS 


the  materials  are  impure.  This  preliminary  trial  entails  very 
little  trouble,  as  one  may  immediately  afterwards  proceed  to  test 
the  print,  adding  it  to  the  other  materials,  and,  if  necessary,  a 
few  drops  more  acid  to  keep  up  a  very  gentle  escape  of  gas. 

Where  sulphocyanide  of  ammonium  is  used  as  a  fixing  agent,  it 
is  probable  that  a  materially  less  amount  of  washing  is  sufficient. 
But  care  must  be  taken  that  the  fixing  has  been  effectual.  This 
may  be  ascertained  by  covering  one-half  of  a  print  and  exposing 
the  other  half  to  a  bright  sunlight  for  three  or  four  hours,  or, 
better,  a  day.  If  any  difference  in  the  purity  of  the  whites  is 
perceptible  in  the  two  halves,  the  fixing  has  been  insufficient. 


§  15. — Finishing  the  Print. 


The  fixed  and  washed  print  will  next  require  to  be  trimmed 
and  mounted. 

When  very  large  quantities  of  prints  are  trimmed,  machines 
are  made  that  cut  them  out  of  the  required  shape  at  a  single 
blow.  This  method  is  peculiarly  suited  to  portraits,  especially 
card  portraits.  Landscape  prints  require  more  attention,  and  the 
trimming  can  often  be  so  regulated  as  to  improve  the  general 
effect. 

An  extremely  convenient  arrangement  is  to  procure  a  thick 
plate  of  glass  with  its  sides  exactly  at  right  angles  to  each  other, 
and  to  rule  on  it  with  a  diamond  a  number  of 
Fig.  124.  lines  parallel  to  the  sides.  Then  resting  the 
plate  on  the  print,  some  one  of  these  lines  is 
kept  parallel  with  a  vertical  or  horizontal  line 
of  a  building,  or  with  the  line  of  the  horizon 
itself.  Then  a  sharp  blade  is  run  round  the 
edges. 

It  is  convenient  to  have  one  end  of  the  plate 

dome-shaped.  The  edges  should  bevel  a  little, 
receding  as  they  rise  from  the  print ;  the  ruling 
should  be  on  the  under  side.* 1 

Some  operators  use  brass  frames.  These  are  very  objection¬ 
able,  as  fine  fragments  are  chopped  off  and  ground  into  the  paper, 


1  These  plates  are  made  and  for  sale  in  London,  but,  apparently,  not  here. 
Mr.  B.  Shoemaker,  of  this  city,  has  made  one  for  the  author,  of  8x10,  a  larger 
size  than  is  kept  in  London.  Probably  when  they  are  better  knowm  here,  they 
will  be  kept  by  dealers. 


SILVER  PRINTING. 


299 


eventually  making  stains.  Steel  edges  to  glass  plates  are  excel¬ 
lent,  but  brass  edges  to  glass  plates  are  to  be  condemned. 

The  trimmed  print  is  next  to  be  attached  to  the  mount  with 
some  adhesive  substance.  Glue  is  undoubtedly  the  best,  but  not 
the  least  troublesome,  and  is  therefore  less  used  than  paste  and 
gum. 

Whatever  is  used  should  be  applied  freely,  and  a  few  minutes 
given  to  swell,  otherwise  the  print  cannot  be  applied  smoothly 
and  evenly  to  the  mount.  Whatever  adhesive  material  is  used, 
should  be  freshly  made.  Sour  paste  is  very  objectionable. 

Many  amateurs  like  to  paste  their  prints  into  scrap-books 
instead  of  mounting  on  cards,  attaching  them  to  the  leaf  by  the 
four  corners  only.  A  good  deal  of  annoyance  is  often  caused  by 
the  cockling  up  either  of  the  print,  the  leaf,  or  both.  The  writer 
finds  that  this  trouble  can  be  'perfectly  avoided  as  follows : — 

Place  some  powdered  gum-arabic  in  a  wide-mouthed  vial  with 
a  long  thick  cork.  Moisten  the  bottom  of  the  cork  with  the 
tongue,  place  it  in  the  bottle,  reverse  it,  and  some  powder  will 
adhere  ;  moisten  again  slightly,  and  gently  rub  the  under  corners 
of  the  print  with  the  cork,  transferring  thus  a  very  thick  muci¬ 
lage,  which  dries  almost  instantly,  and  without  cockling.  No 
one  who  uses  this  method  will  ever  use  any  other.  It  has,  beside 
its  freedom  from  cockling,  the  advantage  of  being  always  ready, 
and  yet  always  affording  a  perfectly  fresh  material,  free  from 
danger  of  sourness,  and  certain  not  to  black  the  corners  of  the 
print. 

Too  little  attention  is  paid  to  the  quality  of  the  pasteboard 
used  for  mounting.  If  this  contain  hyposulphite  of  sodium,  used 
as  “  antichlor”  by  many  papermakers,  the  eventual  destruction 
of  the  print  is  almost  certain,  as  in  damp  weather  enough  moisture 
penetrates  to  transfer  the  hyposulphite  to  the  print.  It  has  been 
affirmed  that  three-fourths  of  all  the  mounts  in  the  market  give 
indications  of  hyposulphite  when  tested  carefully. 

It  is  therefore  no  small  protection  to  the  print  to  have  a  litho¬ 
graphic  “  tint”  printed  on  the  board  for  mounting,  and  extend¬ 
ing  a  short  distance  beyond  the  print  all  round.  In  this  way 
the  transfer  of  soluble  ingredients  from  the  mount  to  the  print 
is  rendered  well-nigh  impossible.  As  various  adhesive  prepara¬ 
tions  adhere  much  less  well  to  thick  “  photographic  tints”  than 
to  ordinary  paper,  it  is  generally  necessary  to  use  good  glue, 
otherwise  the  prints  readily  peel  off. 


300 


PHOTOGRAPHIC  MANIPULATIONS. 


In  damp  weather  the  drying  of  the  adhesive  application  between 
the  two  hard  surfaces  proceeds  slowly,  and  care  must  be  taken 
not  to  pile  up  the  prints  too  soon,  or  the  evaporation  may  be  checked, 
and  the  paste  or  other  material  may  mould,  and  immediately 
stain  the  prints.  Hundreds  are  sometimes  lost  in  this  way  before 
the  danger  is  perceived. 

Bolling. — Prints,  after  mounting,  are  always  rolled,  usually  in 
powerful  presses  between  steel  surfaces.  This  forces  together 
the  fibres  of  the  paper,  gives  a  hard,  fine  surface,  darkens  the 
print  a  little,  and  improves  its  appearance  materially.  It  is  best 
done  just  before  the  print  is  dry  after  mounting.  The  steel  sur¬ 
faces  must  be  kept  bright,  which  is  often  troublesome.  Nickel 
plating  greatly  diminishes  the  trouble  of  preserving  a  high  sur¬ 
face. 

Encaustic  paste  is  prepared  by  dissolving  white  wax  in  essential 
oil  of  lavender,  or  any  other  volatile  solvent,  to  a  pasty  consist- . 
ency.  This  mixture,  well  rubbed  into  a  print  with  a  tuft  of 
flannel,  adds  considerably  to  the  transparency  of  the  shadows, 
and,  in  many  cases,  decidedly  improves  the  picture.  It  has  also 
a  favorable  influence  upon  the  durability  of  the  print.  Salomon, 
whose  prints  are  remarkably  fine,  gives  the  following  formula  : — ■ 


Pure  virgin  wax  .......  5  ounces. 

Gum  elemi  ........  44  grains. 

Benzole  ........  2  ounces. 

Essence  of  lavender  ......  3  “ 

Oil  of  spike . 66  drops. 


Griine  boils  equal  parts  of  white  wax  and  castile  soap  in  an 
earthen  vessel  with  a  little  water,  enough  to  make  a  soft  paste. 

§  16. — Permanence  of  Silver  Prints. 

Great  discredit  has  been  thrown  upon  photography  by  the 
fading  of  silver  prints,  an  effect  which  the  author  believes  to 
have  resulted  from  negligence  in  washing.  A  well  washed  and 
toned  print  is,  according  to  his  experience,  very  durable.  Of 
gold-toned  prints  made  by  the  writer  of  this  manual  not  a  single 
one  has  faded  or  altered  in  any  respect. 

The  writer  believes  that  in  very  many  cases  of  fading,  espe¬ 
cially  of  views  made  for  sale,  there  has  been  no  gold  toning  at 
all,  but  simply  a  sulphur  touing.  With  albumenized  paper  this 
toning  is  sure  in  the  long  run  to  decolorize  very  much,  though 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  301 

some  specimens  on  plain  paper,  executed  by  him  many  years  ago, 
are  still  as  good  and  as  pure  black  as  the  day  they  were  finished. 

The  different  modes  of  gold  toning  seem  all  to  yield  results 
equal  in  respect  of  permanence.  Developed  prints,  although 
gold-toned  with  equal  care,  are  less  permanent,  according  to 
careful  and  extended  experiments  made  by  the  writer,  than  sun- 
prints.  Of  these  last,  the  strongest  seem  to  be  those  that  have 
been  over-printed  enough  to  bear  a  very  full  time  (twenty  minutes 
or  thereabouts)  in  a  strong  fresh  hyposulphite  bath. 


CHAPTER  XIV. 

FAILURES  IN  PHOTOGRAPHIC  OPERATIONS. 

The  beginner  in  photography  will  be  very  apt  to  find  that, 
after  proceeding  reasonably  well  for  a  time,  his  success  suddenly 
terminates  for  some  reason  quite  undiscoverable  to  him.  He 
appears  to  be  proceeding  exactly  as  before,  yet  he  cannot  get  the 
same  results.  A  very  simple  and  useful  course  will  be  to  change 
each  of  his  materials  in  succession,  collodion,  bath,  and  developer, 
and  so  endeavor  to  detect  the  proximate  source  of  the  trouble. 
This  plan  does  not  always,  however,  succeed,  for  the  new  mate¬ 
rial  substituted  may  have  precisely  the  same  fault  as  the  old ;  it 
may  not  be  in  any  respect  bad  or  impure,  but  may  be  simply 
unsuitable  to  the  other  materials  with  which  it  is  employed. 

Hot  only  the  beginner,  but  even  the  experienced  photographer, 
will  occasionally  find  that  things  go  wrong ;  no  one  can  claim 
entire  immunity  from  photographic  troubles.  For  these  reasons 
the  writer  has  endeavored  to  make  this  chapter  a  very  complete 
one,  believing  that  it  will  be  very  frequently  referred  to,  and 
with  advantage.  He  has  collected  the  information  here  given 
partly  from  personal  experience,  but  also  very  largely  from  other 
sources  in  various  languages.  For  convenience  of  reference,  it 
has  been  carefully  classified  under  different  heads : — 


302 


PHOTOGRAPHIC  MANIPULATIONS. 


I.  Failures  Common  to  Negatives,  Ambrotypes,  and  Fer¬ 
rotypes. 

Sec.  1.  Fogging  and  Veiling.  See  page  302. 

“  2.  Thinness  of  Film.  Page  310. 

“  3.  Irregularity  of  Film,  Crapy  and  Structural  Lines,  Gran¬ 

ularity,  Warty  Lumps,  etc.  Page  310. 

“  4.  Transparent  Mottling  at  Corners.  Page  312. 

“  5.  Defects  in  the  Image.  Page  313. 

“  6.  Splitting  and  Slipping  of  the  Film.  Page  316. 

“  7.  Want  of  Sharpness.  Page  317. 

“  8.  Streaks.  Page  318. 

“  9.  Transparent  Spots  and  Pinholes.  Page  321. 

“  10.  Opaque  Spots,  Comets,  etc.  Page  324. 

“  11.  Lines.  Page  326. 

“  12.  Stains  and  Surface  Markings.  Page  327. 

“  13.  Feathery  Markings :  Imperfect  Fixing.  Page  330. 

“  14.  Faults  in  Varnishing.  Page  330. 

“  15.  Miscellaneous.  Page  333. 

II.  Failures  belonging  especially  to  Negatives.  Page 
334. 

III.  Failures  belonging  especially  to  Ambrotypes  and 
Ferrotypes.  Page  335. 

IV.  Failures  belonging  especially  to  Paper  Develop¬ 
ment.  Page  336. 

V.  Silver  Printing. 

1.  Failures  Common  to  Glass  and  Paper  Woric.  Page  336. 

2.  Failures  Peculiar  to  Silver  Printing  on  Paper.  Page  338. 

3.  Failures  Peculiar  to  Collodio-  Chloride  Printing.  Page  342. 


I.  Failures  Common  to  Negatives,  Ambrotypes,  and 
Ferrotypes. 

§  1.— Fogging. 

Fogging  is  a  trouble  that  affects  different  operators  very  vari¬ 
ously  :  some  are  very  frequently,  others  almost  never  affected 
by  it.  The  learner  may  expect  to  be  frequently  troubled;  the 
experienced  operator  will  have  learned  how  to  avoid  it,  except, 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  303 


perhaps,  when  he  works  under  unusual  conditions,  or  with  chemi¬ 
cals  different  from  those  which  he  habitually  employs. 

Before  proceeding  to  the  particular  sources  of  fogging,  some 
observations  of  a  general  nature  may  advantageously  be  made. 

General  Remarks. — When  a  case  of  fogging  presents  itself,  a 
careful  study  of  the  appearance  of  the  plate  will  often  afford  a 
clue  to  the  source  of  the  trouble. 

A  fogged  plate  may  present  a  uniform  sheet  of  blank  fog  all 
over,  without  a  trace  of  a  picture.  Or  an  image  may  come  out 
with  more  or  less  strength,  but,  after  showing  itself,  may  pre¬ 
sently  become  covered  with  a  dense  deposit  of  silver.  Or,  finally, 
the  fogging  may  be  very  slight,  leaving  all  details  of  the  image 
perfectly  visible,  but  ruining  it  by  veiling  the  deep  shadows 
sufficiently  tQ  prevent  them  printing  to  a  full  rich  black. 

The  above  various  cases  are  alike  in  this,  that  the  action  of  the 
fogging  is  uniform  all  over  the  plate.  We,  therefore,  presume 
that  the  trouble  lies  either  in  the  chemicals,  the  light,  or  the 
atmosphere  of  the  dark  room,  and,  if  we  cannot  get  rid  of  the 
evil  by  the  addition  of  a  little  iodine  to  the  collodion,  we  must 
commence  a  series  of  systematic  trials  (see  p.  306),  to  detect  the 
source  of  the  trouble.  We  do  not,  however,  in  the  above  case, 
suspect  the  camera.  For,  if  the  camera  leaks  light,  the  effect  of 
that  light  is  invariably  partial  and  irregular.  The  unequal  con¬ 
traction  and  expansion  of  the  wood  round  the  flange,  into  which 
the  lenses  are  screwed,  will  often  produce  a  crack;  this  will  give 
a  mass  of  fog  somewhat  denser  in  the  middle,  and  shading  off 
towards  the  ends  of  the  plate.  A  hole  in  the  bellows  body  will 
produce  an  irregular  mass  of  fog  on  some  part  of  the  plate  on 
which  the  light  falls.  If  the  dark  slide  does  not  fit  tight,  the 
fogging  will  mostly  be  at  one  end  of  the  plate.  A  crack  in  the 
shutter  will  produce  a  bar  of  fog  lengthwise  of  the  plate,  and 
shading  off  on  both  its  sides.  Cracks  in  the  woodwork  will  send 
in  fan*like  masses  of  light,  and  so  on.  These  appearances  will 
aid  at  once  in  the  detection  of  the  cause  of  the  troubles  (see  also, 
beyond,  “White  Light,”  p.  306). 

Another  very  valuable  distinction  is  drawn  as  follows: — 

A  superficial  fogging ,  one  that  rests  on  the  film  and  not  in  it, 
and  can  be  rubbed  off  with  the  finger,  is  always  attributable  to 
the  chemicals,  never  to  exposure  to  white  light,  which  last  always 
produces  an  action  in  the  interior  of  the  film. 

Therefore,  if  the  fogging  be  internal  and  not  superficial,  it  is 


301  PHOTOGRAPHIC  MANIPULATIONS. 

most  probably  owing  to  intrusion  of  light;  this  cannot  be  affirmed 
with  entire  positiveness,  but  is  the  most  likely  cause,  for  faults  in 
the  bath,  collodion,  etc.,  most  generally  give  rise  to  superficial 
fogging.  That  is,  fog  from  chemicals  is  generally  superficial ; 
superficial  fog  is  always  from  chemicals. 

1.  Chemicals  in  Fault. — Generally  speaking,  when  fog  shows 
itself,  and  when  the  presence  of  white  light  is  not  suspected,  the 
first  thing  done  is  to  treat  the  bath. 

But,  in  all  such  cases,  the  first  step  should  be  invariably  to  try 
another  collodion,  or  to  add  a  little  tincture  of  iodine  to  that  in 
use.  Iodine  tends  to  make  the  bath  slightly  acid.  Therefore,  the 
addition  of  acid  to  the  bath,  or  iodine  to  the  collodion,  is,  in  each 
case,  a  step  in  a  somewhat  similar  direction.  And  it  would  at 
first  seem  more  correct  to  add  the  acid  to  the  bath,  as  that  brings 
the  bath  at  once  to  the  requisite  point  of  acidity,  and  stops  there, 
whereas,  by  adding  iodine  to  the  collodion,  every  plate  tends  to 
render  the  bath  more  acid. 

But,  in  practice,  it  is  found  that  the  results  of  the  two  treat¬ 
ments  are  very  different.  Sometimes  a  very  little  iodine  will 
effect  a  cure  when  acid  seems  to  have  no  effect.  For  example, 
the  writer  has  seen  a  bath  made  of  fused  nitrate  of  silver  abso¬ 
lutely  refuse  to  give  a  clean  picture,  even  when  acidified  beyond 
what  is  proper,  and  yet  work  excellently  by  adding  a  very  little 
iodine  to  the  collodion — a  collodion  which  was  not  new,  but  had 
worked  perfectly  a  month  before,  in  cooler  weather,  with  a  nearly 
neutral  bath. 

When  a  neutral  nitrate  has  been  used,  acidulation  should  not 
be  carried  beyond  one  drop  of  nitric  acid  or  twenty -five  drops  of 
No.  8  acetic  acid  to  every  fifteen  or  twenty  ounces  of  bath,  and 
this  much  is  only  allowable  when  the  nitrate  of  silver  was  free 
from  acid.  When  the  acidifying  has  reached  this  point,  if  the 
picture  is  not  clean,  the  remedy  is  most  certainly  needed  in  the 
collodion.  And  it  must  never  be  forgotten  that  these  treatments 
with  acid  or  with  iodine  are  but  necessary  evils,  and  that  the 
more  nearly  neutral  the  bath  and  collodion  the  more  rapid  will 
be  the  work.  There  appears  to  be  no  doubt  that  excess  of  nitric 
acid  in  the  bath  may  cause  fogging. 

The  bath,  however,  may  have  been  alkaline,  and  may  therefore 
need  neutralizing  and  acidifying.  This  will  be  ascertained  by 
introducing  a  piece  of  red  litmus-paper.  Alkalinity  may  arise 
from  having  introduced  an  alkali  intentionally,  especially  if  am- 


FAILURES  IN  PHOTOGRA-PHIC  OPERATIONS.  305 

monia  have  been  Welded,  previous  to  sunning.  Bicarbonate  of 
sodium  renders  a  bath  rather  neutral  than  alkaline,  and  is  the 
only  substance  that  should  ever  be  employed  for  removing  an 
excess  of  acidity.  Or  alkali  may  have  been  carelessly  introduced, 
when  glasses  cleaned  with  caustic  soda  or  other  alkali  have  been 
insufficiently  washed  before  collodionizing. 

The  use  of  fused  nitrate  of  silver,  that  has  been  kept  too  long 
in  a  state  of  fusion,  or  heated  to  too  high  a  temperature,  may  tend 
to  produce  fog.  Remedy :  add  very  dilute  nitric  acid  very  cau¬ 
tiously,  or  try  an  older  collodion. 

An  old  bath,  highly  charged  with  impurities,  may  lead  to 
fogging.  As  a  palliative,  add  bicarbonate  of  sodium  till  a  per¬ 
manent  ^precipitate  falls,  and  then  expose  for  several  days  to  the 
sun.  Filter,  and  acidify  if  necessary. 

Sometimes  an  old  bath  will  lead  to  fogging,  not  by  reason  of 
impurities,  but  simply  by  having  become  too  weak  by  mere 
exhaustion  of  the  silver.  This  will  be  more  apt  to  happen  with 
baths  whose  evaporation  is  checked  by  being  kept  covered. 
Remedy:  add  crystals  or  fused  nitrate  of  silver. 

Or  the  collodion  may  be  in  fault.  A  very  new  collodion,  espe¬ 
cially  one  containing  little  or  no  alkaline  salt,  but  chiefly  cad¬ 
mium  salt,  particularly  if  used  with  a  nearly  neutral  bath,  will 
sometimes  refuse  to  give  clean,  bright  pictures.  (See  also  p.  136.) 

In  this  case,  especially  if  the  collodion  be  very  pale,  it  is  well 
to  add  to  it  a  little  tincture  of  iodine,  and  so  apply  the  remedy  to 
it  rather  than  to  the  bath.  Or  the  admixture  of  a  little  old  (but 
not  too  old)  and  more  highly  colored  collodion  will  be  found 
useful. 

The  developer  may  be  in  fault.  If,  when  thrown  upon  the 
plate,  it  becomes  almost  immediately  muddy,  more  acetic  acid  is 
wanted.  Or,  a  developer  that  has  hitherto  worked  well,  may 
cease  to  do  so  in  consequence  of  a  change  of  weather  and  tem¬ 
perature. 

It  has  been  affirmed  that  excess  of  acetic  acid  may  produce 
fogging. 

If  copper  be  used  in  the  developer  (sulphate  of  copper,  blue 
vitriol),  and  the  plate  have  been  left  in  the  bath  for  a  time  insuf¬ 
ficient  to  convert  all  the  soluble  iodides  into  iodide  of  silver, 
brown  fog  may  be  produced  by  the  formation  of  iodide  of  copper 
in  the  film. 

Old  specimens  of  pyrogallic  acid  used  in  developing  or  rede¬ 
veloping,  have  been  known  to  produce  blue  fogging . 


306 


PHOTOGRAPHIC  MANIPULATIONS. 


2.  The  vessels  may  be  in  fault.  India-rubber  or  vulcanite  bath, 
or  even  dippers,  may  lead  to  fogging,  and  are  more  likely  to 
when  new  than  old.  In  work  in  the  house,  they  should  never 
be  used.  Even  for  work  in  the  field,  the  writer  advises  a  glass 
bath  with  a  case  and  screw  cover.  But  if  weight  is  very  im¬ 
portant,  and  a  rubber  bath  is  to  be  used,  it  should,  if  new,  be  put 
aside  for  twenty -four  hours  with  a  strong  solution  of  caustic  alkali. 
The  “concentrated  lye,”  sold  in  sheet-iron  boxes,  is  very  good 
for  this  purpose,  and  may  be  dissolved  in  eight  or  ten  times  its 
weight  of  water.  In  the  case  of  an  old  bath,  it  should  be  scrubbed 
out  with  a  sponge  tied  to  a  stick  between  each  using. 

3.  The  ivater  may  be  in  fault.  It  is  said  that  cases  of  fogging 
have  been  traced  to  this  source,  but  the  writer  has  never  expe¬ 
rienced  it.  The  sorts  of  water  said  to  cause  it  are — water  con¬ 
taining  iron;  water  containing  much  lime;  rain-water  collected 
off'  of  dirty  roofs,  or  water  from  wells  into  which  any  decaying 
matter  penetrates,  or  any  foul  drainage. 

4.  White  light  will,  of  course,  cause  fogging.  As  already  said, 
a  careful  examination  of  the  appearance  of  the  plate  will  gene¬ 
rally  indicate  whether  light  has  been  admitted  into  the  dark  room, 
or  has  made  its  way  into  the  camera,  because,  in  the  first  case, 
its  action  extends  uniformly  over  the  whole  plate,  in  the  other  it 
does  not,  but  mostly  appears  in  bars,  fans,  brushes,  or  long  slant¬ 
ing  rays,  the  positions  of  which  will  always  aid  in  tracing  out 
the  cause,  remembering  that  the  more  indistinct  the  boundary 
of  the  fog  the  farther  is  probably  the  opening  or  leak  from  the 
plate. 

A  few  systematic  trials  will  always  force  out  the  source  of  the 
fault. 

Develop  a  plate  without  exposure  and  without  removing  it 
from  the  dark  room.  If  no  tendency  to  fog  appears,  the  fault 
was  clearly  in  the  camera  or  the  dark  slide.  Then  sensitize  a 
plate  and  carry  it  into  the  glass  room  in  its  dark  slide.  Leave  it 
a  few  minutes  and  develop  it  again  without  having  exposed  it  or 
withdrawn  the  shutter.  If  it  then  fogs,  the  leak  is  in  the  dark 
slide;  if  not,  then  it  must  be  in  the  camera. 

Let  us,  on  the  other  hand,  suppose  that  the  plate  fogged,  when 
developed,  without  having  been  removed  at  all  from  the  dark 
room.  Then  the  fault  is,  either  that  white  light  gets  into  the 
dark  room,  or  the  chemicals  are  in  fault. 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  307 


A  simple  way  of  deciding  this  is  to  try  a  plate  at  night.  Use 
only  a  candle  or  lamp,  well  protected  with  yellow  or  green  glass. 
Sensitize  a  plate,  lay  it  on  a  dark  object,  put  a  worthless  negative 
over  it,  and  carry  it  into  another  room,  in  which  is  a  gaslight, 
turned  on.  Hold  the  plate  a  foot  from  the  burner  for  fifteen 
seconds,  taking  care  that  the  back  is  perfectly  protected.  Then 
carry  and  develop,  by  the  light  of  a  lamp  or  candle,  behind  yel¬ 
low  glass.  If  a  clean  picture  comes  out,  it  is  a  proof  that  white 
light  gets  into  the  dark  room  in  daytime.  If  it  fogs  still,  when 
tried  thus,  the  chemicals  are  wrong,  and  must  be  changed,  one 
after  another,  until  the  wrong  one  is  detected. 

This  simple  but  systematic  and  exhaustive  search  will  invari¬ 
ably  lead  the  operator  straight  to  the  source  of  his  trouble. 

If  the  foregoing  examination  shows  the  fault  to  be  with  the 
camera,  it  must  be  carefully  overhauled.  Carelessly  made  cameras 
are  quite  worthless,  and  a  great  many  such  are  exposed  for  sale. 
The  writer  dislikes  walnut,  although  this  wood  is  so  great  a 
favorite,  because  it  cracks  so  much,  and  prefers  mahogany,  and 
next  to  it,  cherry.  Look,  therefore,  carefully  for  cracks.  Exa¬ 
mine  if  the  shutter  works  close  in  the  dark  slide.  Notice  if  a 
hole  has  been  worn  into  the  bellows  body.  But  the  commonest 
place  to  crack  is  the  camera  front,  which  often  splits  at  the  screws 
that  fasten  the  flange  in.  When  a  crack  once  appears,  do  not 
trust  to  filling  it  up,  but  get  a  new  front.  A  crack  slowly  widens, 
and  so  leaves  a  space  between  the  edges  and  the  filling.  A  crack 
may,  however,  be  neatly  mended  by  a  good  workman.  The  front 
is  cut  half-way  through  at  the  crack,  for  half  an  inch  each  side, 
and  a  piece  set  in.  Then  if  the  crack  widens,  it  can  do  no  harm, 
and  another  crack  is  not  likely  ever  to  form,  as  the  tension  that 
caused  it  has  been  relieved. 

When  a  camera  is  used  in  the  open  air,  it  must  invariably  be 
covered  with  a  thick  cloth.  Strong  light,  especially  direct  sun¬ 
light,  will  make  its  way  through  almost  any  camera,  unless  so 
protected. 

5.  Sunlight  falling  directly  upon  the  lens  may  cause  fogging, 
though  this  result  does  not  necessarily  follow. 

6.  Atmospheric  Causes. — The  sources  of  fogging  may  depend 
upon  impurities  in  the  air.  These  may  be  of  several  sorts. 

A.  Chemical. — Fumes  of  various  sorts  may  cause  fogging. 
Ammonia  is  especially  to  be  avoided.  See  that  the  ammonia 


808 


PHOTOGRAPHIC  MANIPULATIONS. 


bottle  has  a  well-fitting  glass  stopper — not  a  cork.  Sulphuretted 
hydrogen,  arising  from  exposure  of  solutions  of  sulphide  of  potas¬ 
sium,  or  of  Schlippe’s  salt,  is  even  worse. 

B,  Certain  organic  substances  have  a  tendency  to  cause  fogging. 
The  vapor  of  turpentine  and  of  fresh  paint.  The  smell  of  kero¬ 
sene  lamps  in  the  dark  room  does  not  seem  to  be  hurtful,  as  might 
be  supposed. 

0.  Foulness  in  the  air  is  liable  to  cause  fogging.  Emanations 
from  drains,  cesspools,  and  the  like,  or  any  putrefying  or  decay¬ 
ing  organic  matter.  Emanations  from  stables  are  always  ammo- 
niacal,  and  tend  to  fogging.  It  should  be  borne  in  mind  that 
immunity  from  these  sources  at  one  time,  is  no  proof  that  they 
may  not  be  acting  at  another.  Dampness  acts  very  remarkably 
as  a  vehicle  for  odors,  and  emanations  may  rise  in  wet  weather  so 
as  to  cause  fogging,  when  they  would  not  at  other  times.  Inde¬ 
pendently  of  this,  the  state  of  the  barometer  controls  currents  and 
movements  of  air  remarkably.  When  the  barometer  is  rising,  a 
room  will  be  supplied  with  air  from  channels  quite  different  from 
those  that  act  when  the  barometer  is  falling.  Drafts  of  chimneys 
are  always  worse  with  a  rising  barometer.  Whether  carbonic 
oxide ,  the  gas  which  flues  are  intended  to  carry  away  from  fires, 
will  cause  fogging,  the  writer  cannot  state,  but  no  one  is  justified 
in  permitting  this  most  dangerous  gas  to  escape  into  apartments 
by  defective  flues.  Its  danger  is  not  greatest  when  it  asphyxiates, 
for  then  the  evil  is  noticed  in  time,  and  remedies  are  applied. 
But  if  inhaled  continually  in  small  quantities,  it  causes  diseases 
of  the  brain  and  spine.  Leakage  of  illuminating  gas  may  cause 
fogging. 

7.  Errors  of  Manipulation. — Under  this  head  the  following  are 
to  be  classed : — 

a.  Plate  left  too  long  in  the  bath.  This,  especially  in  warm  weather, 
is  a  fruitful  cause  of  foggy  plates.  When  the  plate  is  perfectly 
free  from  oiliness,  it  is  ready  for  removal.  The  sensitiveness  in¬ 
creases  by  leaving  in  for  a  full  time;  the  brightness  and  cleanness 
are  greatest  when  the  plate  is  taken  out  as  soon  as  the  oily  lines 
are  gone.  In  the  latter  case,  undecomposed  bromide  remains  in 
the  film,  diminishes  sensibility,  but  checks  veiling  and  fogging. 

b.  Too  long  a  development ,  rendered  necessary  by  too  short  an 
exposure. 

c.  Neglect  to  add  acid  to  the  developer  or  the  redeveloper. 

d.  Insufficient  washing  off  of  the  developer,  so  that  enough 
remains  to  act. 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  309 


e.  Considerable  over-exposure  with  a  large  stop  will  produce  fog¬ 
ging,  or  rather  an  appearance  closely  resembling  the  effect  of  fog. 

f.  Re-dipping  the  plate  into  the  negative  bath  before  development 
is  very  apt  to  cause  stains  and  fog,  especially  with  a  bath  not  in 
first-rate  order. 

g.  Too  strong  a  developer ,  or  using  in  summer  a  developer  suit¬ 
able  for  winter. 

h.  Keeping  on  the  developer  after  spangles  of  silver  show  in  it. 

i.  Developer  turns  muddy  at  once.  Developing  vessel  not  duly 
cleaned.  Use  the  bichromate  solution.  Bad  condition  of  the 
nitrate  bath.  Keeping  and  using  pyrogaliic  acid  dissolved  in 
water  instead  of  alcohol. 

In  the  case  of  glass  positives,  fogging,  when  superficial,  may 
be  wiped  off  carefully  with  soft  cotton-wool. 

7.  Temperature  of  the  Dark  Room. — Either  extreme  of  tempera¬ 
ture  may  cause  fogging.  In  very  hot  weather,  use  less  iron  and 
more  acetic  acid.  Some  operators  find  it  advantageous  to  place 
the  bath  in  a  vessel  of  cold  water,  to  keep  down  the  temperature. 

In  very  cold  weather ,  if  the  dark  room  be  not  artificially  heated, 
the  chemicals  will  not  act  well.  Great  perplexity  is  sometimes 
caused  to  inexperienced  operators  in  this  way,  who  will  perhaps 
suddenly  find  that  they  pass  from  success  to  failure  without  any 
assignable  reason,  and  only  learn  by  the  most  painful  experience 
the  real  source  of  their  trouble.  A  temperature  of  about  65°  is 
always  the  best,  though  considerable  variation  may  occur  before 
evil  results. 

Veiled  (that  is,  very  slightly  fogged)  negatives  often  print  as 
well  as  brighter  looking  ones.  If  the  veiling  reaches  the  extent 
of  slight  fogging,  a  clearing  process  may  be  resorted  to  in  either 
of  several  ways.  A  very  weak  solution  of  sesquichloride  of  iron 
may  be  washed  over  the  plate.  Or  it  may  be  washed  a  little 
with  weak  Lugol’s  solution,  and  then  thrown  into  the  fixing 
bath.  Or  the  plate  may  be  chlorized  (see  article  on  After-inten¬ 
sification)  to  a  very  moderate  extent,  and  then  passed  through 
the  fixing  bath.  Whichever  plan  is  adopted,  experience  should 
be  first  gained  on  worthless  negatives. 

8.  Dew  Collecting  on  the  Lens. — In  hot  damp  weather  dew  may, 
at  any  time,  collect  upon  the  lens  almost  in  a  moment.  This  is 
especially  apt  to  happen  in  passing  from  a  cool,  shaded  spot  to  a 
warm,  damp  one.  Watchfulness  for  this  cause  of  trouble  will  be 
particularly  needed  in  warm,  damp,  steamy  weather. 


310 


PHOTOGRAPHIC  MANIPULATIONS. 


9.  In  portraiture,  an  excess  of  diffused  irregularly  reflected 
light  may  veil  the  plate. 


§  2. — Thinness  of  the  Film. 

A  thin  gray  film ,  so  appearing  when  removed  from  the  sensi¬ 
tizing  bath,  may  be  caused  by  too  strong  a  bath,  which  at  first 
acts  rapidly  upon  the  film,  but  gradually  diminishes  its  density. 
This  is  the  case  with  ordinary  collodion.  With  a  collodion  con¬ 
taining  bromide  only,  intended  for  the  dry  process,  thinness  of 
the  film  results  from  too  weak  a  bath. 

A  thin  bluish  film ,  with  wet  plates,  indicates  insufficient  salting 
of  the  collodion,  or  insufficient  time  in  the  bath.  With  collodio- 
bromide  plates,  it  indicates  that  the  collodion  has  not  stood  long 
enough  after  sensitizing. 

Yery  old  collodion  will  sometimes  give  very  thin,  transparent 
films,  as  will  also  a  foul  nitrate  bath. 


\  8. — Irregularity  of  the  Film,  Crapy  and  Structural  Line,  Warty 
Lumps,  Granularity,  &c. 

Crapy  Lines.— 1.  Too  watery  alcohol  or  ether.  (Fig.  125, 
lower  corner.) 

It  does  not  necessarily  follow  that  the  materials  are  in  fault  as 
purchased,  for  the  water  may  have  been  in¬ 
advertently  introduced  by  the  photographer 
himself.  After  cleaning  a  bottle,  in  which 
collodion  is  to  be  made,  proceed  as  follows : 
Drain  it  well,  pour  in  an  ounce  or  two  of  al¬ 
cohol,  shake  well  so  that  the  alcohol  wets 
every  part,  pour  it  out,  and  repeat  the  opera¬ 
tion.  The  quantity  of  water  that  may  be  in¬ 
troduced  by  a  wet  bottle  is  more  than  would 
be  supposed. 

2.  Neglect  to  rock  the  plate  from  side  to 
side,  after  collodionizing,  especially  when  using  a  rather  thick 
collodion.  If  this  is  the  case,  thin  with  equal  parts  alcohol  and 
ether.  Before  deciding,  however,  that  the  collodion  requires 
thinning,  the  operator,  if  not  experienced,  should  endeavor  to 
satisfy  himself  that  the  fault  is  not  in  his  manipulation:  thinning 
should  not  be  unnecessarily  resorted  to. 


Fig.  125. 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  311 

The  larger  the  plate  the  thinner  must  be  the  collodion.  A 
small  plate  can  be  managed  with  a  collodion  which  will  inevita¬ 
bly  give  crapy  lines  when  used  for  a  large  one. 

Excessive  cold  may  produce  crapy  lines. 

Ridges. — 1.  Too  much  pyroxyline  in  collodion.  2.  Too  much 
alcohol  and  too  little  ether.  (Both  these  defects  are  cured  by 
adding  a  little  ether.)  3.  Excess  of  ether  may,  however,  produce 
a  similar  effect.  4.  Bad  cotton,  tending  to  gelatinize;  or  the  col¬ 
lodion  may  have  become  too  thick  by  the  agency  of  bromide  of 
cadmium.  The  action  of  this  substance  upon  collodion  is  very 
remarkable,  and  varies  extremely  at  different  times. 

Mottling  may  arise  from  irregularity  in  the  porosity  of  the  film, 
so  that  the  developer  penetrates  irregularly.  It  usually  results 
from  using  too  thick  a  collodion;  sometimes  from  not  plunging  the 
plate  into  the  bath  soon  enough  after  coating.  Mixing  with 
ether  and  immersing  as  soon  as  set  will  usually  remove  this 
trouble,  which  is  most  apt  to  show  itself  in  the  flat  tints,  espe¬ 
cially  in  semi-opaque  skies.  Or  it  may  arise  from  a  bad  quality 
of  cotton.  Cottons  vary  extremely  in  this  respect;  some  have 
much  tendency  to  mottling,  others  none  at  all.  Or  the  alcohol 
may  be  too  watery. 

Collodion  that  has  thickened  through  the  agency  of  bromide  of 
cadmium,  may  be  made  to  work  by  mixing  with  very  fluid  collo¬ 
dion.  Much  circumspection  is,  however,  needed.  The  mixture 
should  stand  for  several  days,  with  occasional  shaking,  and  then 
be  carefully  filtered. 

Blistering  is  not  a  common  fault,  but  arises  from  using  a  too 
old  and  rotten  collodion. 

Warty  Lumps. — As  the  collodion  film  dries  after  coating,  any 
solid  particles  present  collect  around  them  a 
portion  of  the  collodion,  making  little  raised 
prominences.  Most  commonly,  these  are 
caused  by  fine  filaments,  either  of  wool,  from 
the  dust  caused  by  wear  of  clothes  and  car¬ 
pets,  or  of  undissolved  fibres  of  pyroxyline. 

These  little  warty  places,  examined  with  a 
microscope,  present  the  appearance  seen  at 
Fig.  126.  When  motes  are  visible  as  the  film 
flows  over  the  plates,  they  can  often  be  floated 
off  by  pouring  on  an  abundant  quantity,  and 
managing  to  make  the  collodion,  as  it  flows  off,  carry  away  the 


Fig.  126. 


A  warty  lump  magni¬ 
fied,  showing  a  filament 
nucleus. 


312 


PHOTOGRAPHIC  MANIPULATIONS. 


mote.  Careful  filtering  of  the  collodion,  and  thorough  brushing 
off  of  the  plate  immediately  before  coating,  are  the  best  preventives. 
In  field  work  it  is  often  best  to  take  several  small  bottles  of  col¬ 
lodion  rather  than  one  larger  one. 

Want  of  homogeneity  in  the  collodion  must  result  in  irregu¬ 
larity  of  density  and  streakiness.  If  different  collodions  be 
mixed  without  sufficient  shaking ;  collodion  that  drains  off  from 
the  plate  is  always  denser,  and  sinks  to  the  bottom  if  drained  off 
into  other  collodion.  By  standing  a  long  time,  the  mixed  collo¬ 
dion  may  become  homogeneous  by  diffusion,  but  it  is  unsafe  to 
trust  to  this. 

Again,  suppose  the  drainings  from  the  plates  have  been  re¬ 
ceived,  as  they  alwaj^s  should  be,  into  a  separate  bottle,  and  that 
a  quantity  of  such  be  filtered  in  a  collodion  filter,  of  which  the 
bottom  part  is  already  partly  filled  with  collodion,  each  drop 
will  sink  to  the  bottom,  and  the  two  collodions  will  remain  quite 
separate.  If  poured  out,  and  handled  carelessly,  there  will  be 
formed  an  irregular  mixture  which  cannot  diffuse  itself  with 
perfect  regularity  over  glass  plates. 

Therefore,  collodions  either  should  be  kept  thoroughly  separate, 
or,  if  mixed,  should  be  mixed  thoroughly  by  shaking,  and  then 
be  either  filtered  in  separate  lots,  or  allowed  to  settle  separately. 
Those  curious  to  observe  the  action  of  collodions  in  mixing,  can 
tinge  one  portion  with  a  little  rosaniline,  by  which  means  it  can 
be  distinguished  in  its  movements. 

Granularity. — After  a  certain  time  of  action,  the  iron  developer 
will  always  become  muddy ;  and  if  allowed  to  remain  on  the  plate 
in  this  condition,  it  may  fog ;  or,  if  it  does  not,  it  will  probably 
form  a  gray,  granular  deposit,  destructive  to  the  fineness  of  the 
negative.  A  negative,  to  give  a  rich,  velvety  print,  should  be 
made  up  of  an  extremely  fine  silver  deposit.  Too  much  bromide 
in  the  collodion  will  also  cause  granularity  in  the  image. 

§  4. — Transparent  Mottling  at  one  Corner  of  the  Plate. 

This  is  owing  to  the  heat  of  the  fingers.  It  will  be  found  that 
these  marks  always,  come  at  the  corner  by  which  the  plate  was 
held  whilst  being  collodionized.  (See  Fig.  125,  upper  corner.) 
Often,  if  the  plate  be  held  up  to  the  light  before  putting  into  the 
dark  slide,  these  irregularities  will  be  perfectly  visible. 

What  is  remarkable  is  that,  in  the  great  majority  of  instances, 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  313 


the  plate  can  be  held  without  this  result  following.  It  appears 
to  come  only  with  certain  temperatures  and  conditions  of  the 
atmosphere,  and  principally  in  cool  weather.  The  remedy  is  to 
fold  up  a  piece  of  paper,  and  keep  it  between  the  finger-ends  and 
the  bottom  of  the  plate.  In  fact,  this  sort  of  marking  is  so  great 
an  annoyance  where  it  comes,  and  so  irregular  in  its  coming,  that 
it  is  a  good  plan  always  to  use  the  paper ;  it  is  little  trouble,  and 
the  cure  is  perfect. 

In  making  dry  plates,  this  precaution  should  never  be  neglected. 

This  sort  of  mottling  can  always  be  distinguished  from  that 
which  arises  from  bad  cotton  or  bad  alcohol  (see  last  section)  by  the 
marks  corresponding  with  the  shape  and  position  of  the  fingers. 


§  5. — Defects  in  the  Image. 

Image  strong  but  coarse.  Too  much  pyroxyline. 

Image  fine  but  weak.  Too  little  pyroxyline. 

Too  much  Contrast. — 1.  Under  exposure  followed  by  over-de¬ 
velopment  is  by  far  the  most  common  cause.  2.  Too  little  py¬ 
roxyline  in  the  collodion.  3.  Bromide  either  wanting  entirely 
or  too  little  of  it.  4.  The  introduction  of  a  great  deal  too  much 
bromide  will  produce  the  same  effect.  That  is,  a  little  too  much 
bromide  will  make  the  image  too  flat,  whilst  a  still  greater  excess 
will  render  it  harsh.  5.  Acidity  of  collodion.  (See  also  §13,  Insen¬ 
sitiveness.)  6.  Use  of  old,  red  collodion.  7.  It  has  been  said 
that  alkalinity  of  collodion  may  also  produce  this  defect.  8. 
Insufficient  salting  of  collodion.  9.  Old  and  foul  nitrate  bath. 
Although  by  good  management  a  negative  bath  can  be  kept  in 
working  order  for  a  very  long  time,  still  the  best  rendering  of 
strong  contrasts  will  always  be  made  by  a  nearly  new  and  pure 
bath.  Shaded  foliage  in  well-lighted  scenes  and  instantaneous 
effects  will  be  better  rendered  by  plates  made  under  these  con¬ 
ditions.  If  the  bath  wants  sunning,  it  may  be  expected  to  give 
harsh  pictures.  10.  Too  intense  a  pyroxyline.  11.  Working  in 
too  cold  temperatures. 

Too  Little  Contrast. — 1.  Over-exposure.  2.  Too  much  bromide. 
3.  Alkaline  collodion. 

Too  Much  Vigor. — Powerful,  slow-printing  negatives,  requiring 
sunshine  and  long  exposure  to  print,  come  with  a  thick,  highly 
salted  collodion  and  rich  nitrate  bath.  Such  will  need  to  be 
printed  with  a  weak  positive  bath  and  sunlight. 

21 


314 


PHOTOGRAPHIC  MANIPULATIONS. 


Too  Little  Vigor.— Good  negatives,  except  that  they  are  thin, 
yet  very  delicate  and  full  of  detail,  are  got  with  fluid  collodion, 
lightly  salted  and  sensitized  in  weak  baths.  Such  will  need  a 
rich  positive  bath,  and  printing  in  the  shade. 

This  fault  may  arise  from  under  or  over  exposure,  the  effects 
of  which  are,  however,  different.  In  the  under-exposed  image, 
the  least  defective  parts  will  be  the  high  lights  of  the  object, 
which  will  in  general  be  good,  and  the  worse  lighted  parts  will 
be  defective.  Where  the  picture  is  over-exposed,  the  reverse 
will  be  the  case.  Generally  speaking,  in  an  under-exposed  pic¬ 
ture,  especially  after  redevelopment,  the  contrasts  will  be  too 
great.  An  over-exposed  picture  will  be  gray  and  feeble,  and 
deficient  in  contrast. 

It  may  easily  happen  that  a  negative  may  be  condemned  as 
thin  and  flat,  when  in  reality  it  may  need  nothing  else  than 
printing  on  paper  sensitized  with  a  materially  richer  positive 
bath. 

Weakness  may  also  arise  from  exhaustion  of  the  negative  bath, 
in  which  case  it  must  receive  more  nitrate  of  silver.  Now  that 
more  bromide  is  used  in  the  collodion,  a  thirty-grain  bath  is  no 
longer  sufficient,  but  forty  to  forty-five  grains  give  a  better  result. 
The  employment  of  these  strong  nitrate  baths  has  become  much 
more  general  than  at  the  time  when  the  first  edition  of  this 
manual  was  published.  A  strong  negative  bath  tends  to  keep 
the  iodide  and  bromide  of  silver  (and  consequently  the  image) 
within  the  film.  A  weak  bath  tends  to  give  a  superficial  image. 

Thin  White  or  Gray  Image  difficult  to  Intensify. — This  is  gene¬ 
rally  the  result  of  having  too  much  nitric  acid  in  the  bath.  Add 
a  very  little  bicarbonate  of  sodium.  If,  at  the  same  time,  the 
bath  gives  pinholes,  dilute  it,  render  it  alkaline  with  bicarbonate 
of  sodium,  sun  it,  filter,  and  then  faintly  acidulate. 

The  following  causes  are  assigned  by  Hardwich  as  leading  to 
weak  and  slaty-blue  images:  Negative  bath  newly  made  with 
impure  crystals  of  nitrate  of  silver.  Too  much  free  iodine  in  the 
collodion.  Camera  image  very  weak,  as  in  copying  old  manu¬ 
scripts,  etc.,  full  size.  Use  of  a  negative  collodion  made  from 
weak  pyroxyline.  Sulphuric  acid  left  in  the  collodion  from  im¬ 
perfect  washing.  Coating  large  plates  too  leisurely  in  hot 
weather :  the  film  dries,  and  there  is  no  penetration  of  the  de¬ 
veloper.  Over-exposure. 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  315 


Half  Tone . — The  greatest  beauty  of  result  will  always  depend 
upon  the  presence  of  plenty  of  varied  half-tone,  relieved  and 
supported  by  a  certain  quantity  of  deep  shadows  and  high  lights. 
A  negative  that  consists  chiefly  of  dark  shadows  and  bright  lights, 
with  but  little  half-tone,  will  always  be  greatly  inferior  in  effect. 
Nothing  can  compensate  for  the  absence  of  these  broad  soft  half¬ 
shades,  which  are  abundantly  present  in  all  good  work.  No 
royal  road  to  this  result  can  be  indicated:  it  comes  by  a  full, 
but  not  excessive,  exposure;  collodion  well,  but  not  excessively, 
bromized ;  careful  arrangement  of  light;  and  judicious  develop¬ 
ment.  Those  who  find  great  difficulty  in  subduing  contrast  may 
find  it  a  valuable  hint  to  increase  their  exposures,  and  dilute  their 
developer  proportionately,  as  otherwise  the  prolonged  exposure 
might  lead  to  flatness. 

Two  Images  at  Once. — Imperfect  cleaning.  Remedy :  Use  the 
bichromate  mixture. 

Blurring  or  Halation. — Several  different  sorts  of  blurring  pre¬ 
sent  themselves. 

1.  Internal  reflection,  i.  e.,  from  the  back  surface  of  the  glass. 
This  vexatious  evil  occurs  in  proportion  to  the  transparency  of 
the  film,  except  that,  in  the  wet  process,  there  is  apparently  left  a 
portion  of  iodide  and  bromide  unconverted,  at  the  bottom  of  the 
film,  which  tends  to  check  it.  Therefore  this  difficulty  exists 
less  in  wet  than  in  dry  plates.  Nevertheless,  wet  plates  are  far 
from  being  free  from  it.  In  taking  views  of  interiors,  the  win¬ 
dows  are  apt  to  be  blurred.  Generally  speaking,  blurring  shows 
itself  most  where  a  brilliant  light  comes  next  to  a  deep  shadow. 
Especially  where  a  dark  portion  is  surrounded  by  high  lights, 
as  in  the  case  where  dark  objects  are  projected  against  the  sky, 
or,  still  more,  against  bright  clouds.  In  this  way,  roofs  of  houses, 
instead  of  being  bordered  by  a  well-defined  line,  will  shade  off*, 
as  it  were,  into  the  sky.  Small  objects  projected  against  the  sky, 
as,  for  example,  a  lightning-rod,  may  be  obliterated  almost  en¬ 
tirely.  With  wet  plates  the  remedy  is  to  apply  a  piece  of  wet 
red  blotting-paper ;  with  dry  plates,  to  paint  the  back  with  a 
mixture  of  annatto,  glycerine,  and  water,  as  directed  under  the 
head  of  dry  plate  work. 

2.  Where  a  high  light  meets  a  dark  shadow,  if  the  portion  of 
the  light  next  the  shadow  is  too  light,  the  result  is  that  the  dark 
object  is  surrounded  by  a  light  band.  This  is  only  seen  in  wet 


316 


PHOTOGRAPHIC  MANIPULATIONS. 


plate  work.  In  the  shadow,  the  development  consumes  but  little 
of  the  nitrate  of  silver,  so  that  the  adjoining  part  of  the  high 
light  is  developed  in  the  presence  of  a  solution  richer  in  silver 
than  the  rest  of  it. 

3.  The  image  seems  to  slide  off  into  the  portion  next  below. 
This  only  happens  with  wet  plates,  and  in  cases  of  difficult  de¬ 
velopment,  owing  to  a  cold  temperature,  a  weak  image,  etc. 

4.  Objects  moved  by  the  wind  are  also  blurred.  If  a  bough 
be  projected  against  the  sky,  and  moves  during  exposure,  the 
white  light  from  the  sky  may  almost  obliterate  the  image  of  the 
bough.  Any  blurring  by  the  wind  produces  a  most  disagree¬ 
able  effect  upon  the  picture. 

Part  of  the  Image  weaker  than  the  Pest ,  with  a  distinct  Boundary. 
— This  is  occasioned  by  not  carrying  the  developer  over  the 
whole  plate  with  a  single  sweep. 

Irregular  Refractions. — When  a  piece  of  smooth  ground  inter¬ 
venes  between  the  camera  and  the  objects,  a  strong  sun  falling 
upon  the  ground  may  give  rise  to  irregular  movements  of  rarefied 
air,  which  are  capable  of  destroying  the  sharpness  of  that  part  of 
the  image  that  is  just  over  the  line  of  the  ground. 

§  6. — Splitting  and  Slipping  of  the  Film. 

1.  Splitting  in  Sensitizing  Bath. — 1.  Immersing  too  soon  in  the 
bath,  before  the  film  is  properly  set.  2.  Ill-cleaned,  greasy,  or 
damp  glass.  3.  Omitting  to  roughen  the  edges.  4.  Too  much 
alcohol  in  the  collodion.  5.  Too  much  salting.  6.  Alcohol  too 
watery.  7.  Immersing  the  plate  too  roughly.  8.  Pyroxyline 
made  in  too  strong  acids. 

2.  Splitting  in  Washing. — Bad  quality  of  pyroxyline;  also,  the 
faults  above  enumerated  may  exert  their  influence  in  the  washing 
as  well  as  in  the  sensitizing. 

3.  Splitting  in  Drying. — This  may  also  be  the  fault  of  the 
pyroxyline,  but  it  is  apt  to  result  from  the  treatment  which  the 
film  has  received.  Much  redevelopment  with  pyrogallic  acid 
and  silver  is  very  apt  to  cause  the  film  to  split.  Treatment  with 
mercury  for  forcing  (which  see)  also  makes  the  film  very  tender. 
Remedy  :  coat  the  rest  of  the  plates  (when  warned  by  one  split¬ 
ting)  that  are  in  danger,  with  a  solution  of  gum  in  water,  about 
thirty  grains  to  the  ounce,  or  with  one  of  gelatine,  about  half  as 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  317 

strong.  This  will  not  take  the  place  of  varnishing,  which  must 
be  done  as  usual,  unless  but  few  copies  are  wanted,  and  little 
value  is  attached  to  the  plate. 

Splitting  in  drying  may  also  arise  from  an  insufficient  quantity 
of  pyroxyline  in  the  collodion,  or  from  too  large  a  proportion  of 
ether.  Too  alkaline  a  collodion  gives  a  weak  film. 

In  the  case  of  dry  plates,  a  tendency  to  split  at  the  edges  will 
occur  with  some  sorts  of  cotton  that  otherwise  are  all  that  can 
be  desired.  In  such  cases  edge  with  solution  of  rubber  in  ben¬ 
zole,  not  only  before  coating  as  usual,  but  a  second  time  before 
developing. 

Slipping  off  of  the  Film. — Omitting  to  roughen  the  edges.  Bad 
or  imperfect  cleaning.  Old  and  acid  negative  bath.  Immersing 
too  quickly.  Pyroxyline  of  bad  quality,  or  too  old. 

§  7. — Want  of  Sharpness. 

1.  The  necessity  for  having  the  sensitive  film  occupy  the  pre¬ 
cise  position  of  the  ground  glass,  has  been  before  dwelt  on. 
Without  the  nicest  attention  to  the  perfect  adjustment  of  the 
camera  in  this  respect,  perfect  sharpness  is  impossible.  Careless 
focussing  may  also  have  been  done.  And  some  lenses  have  no 
focus  at  all,  but  may  be  racked  in  and  out  for  half  an  inch, 
without  great  variation,  being  really  sharp  nowhere.  Such  are, 
of  course,  worthless,  and  with  a  bad  lens  nothing  can  be  accom¬ 
plished.  It  will  sometimes  happen  that,  after  a  lens  has  been 
taken  to  pieces  to  clean,  the  parts  will  be  put  together  wrongly, 
either  through  simple  inadvertence  or  from  want  of  knowledge. 
When  bad  results  are  got,  they  seem  inexplicable,  and  perhaps 
the  optician  is  blamed  for  sending  out  a  bad  lens.  The  figures 
in  the  earlier  portion  of  this  book  will  show  the  proper  arrange¬ 
ment  of  the  parts  of  the  various  combinations. 

2.  Camera  Moving  During  the  Exposure. — This  may  arise  from 
carelessness  or  from  the  wind.  A  simple  mode  of  avoiding  the 
latter  consists  in  fastening  a  string  to  the  under  part  of  the  tripod 
head  which  hangs  down  and  ends  with  a  loop  reaching  nearly  to 
the  ground.  The  foot  placed  in  this  loop  and  pressed  forcibly 
down,  holds  the  camera  securely  in  its  position,  supposing  always 
that  the  legs  rest  on  a  hard  surface.  On  a  yielding  surface,  the 
legs  might  sink  during  the  exposure,  enough,  at  least,  to  destroy 
the  sharpness. 

3.  Want  of  coincidence  between  the  chemical  and  visual  foci. 


818 


PHOTOGRAPHIC  MANIPULATIONS. 


§  8. — Streaks. 

There  are  several  causes  that  are  fruitful  in  streaks  which  may 
utterly  ruin  the  negative. 

1.  Immersing  the  Plate  too  Rapidly. — The  mixed  alcohol  and 
ether,  with  which  the  film  is  saturated,  gives  it  a  repellent  action 
to  the  bath  solution,  and  if  the  plate  be  rapidly  lowered  into  it, 
parallel  streaks  may  follow.  As  some  collodions  are  more  repel- 
lant  than  others,  a  degree  of  rapidity  may  produce  this  result 
with  one  that  does  not  with  another. 

2.  Removing  too  soon  from  the  Negative  Bath. — When  this  has 
been  done,  oily-looking  branching  lines  may  be  seen  at  once,  if 
the  reflection  of  a  light  be  caught  on  the  surface  (for  this  reason 
the  light  ought  to  be  arranged  with  special  reference  to  observing 
the  surface  of  the  plate  as  it  is  removed  from  the  bath).  These 
streaks  will  appear  in  the  development. 

8.  Repellent  Action  of  the  Film  on  the  Developer. — The  developer 
for  an  old  bath  must  always  contain  a  certain  amount  of  alcohol 
to  keep  up  its  relation  with  the  bath  solution.  When  the  nega¬ 
tive  bath  is  charged  with  alcohol  and  ether,  the  developer  may 
cease  to  mix  quickly  and  evenly  with  the  bath  solution  on  the 
plate,  and  may  collect  on  it  in  ridges ;  under  these  ridges  the 
plate  develops  faster,  and  consequently  they  are  represented  by 
dark  streaks  in  the  image.  (See  B,  Fig.  127.)  One  point  is  es¬ 
pecially  worthy  of  attention.  Often  the  developer  on  the  film  is 
in  a  condition  that  it  just  barely  holds  together  in  an  even  film 
so  long  as  the  plate  is  level,  ready  to  break  into  ridges  the 
moment  the  plate  is  tilted  up  to  look  through,  for  the  purpose  of 
judging  whether  it  is  sufficiently  developed.  The  moment  this 
breaking  up  takes  place,  the  development  becomes  unequal,  and 
streaks  are  formed.  Numbers  of  otherwise  successful  plates  are 
spoiled  in  the  development  in  this  way,  and  the  danger  must 
constantly  be  borne  in  mind.  Generally  it  may  be  said  that 
(unless  the  operator  is  quite  sure  that  his  materials  have  no  ten¬ 
dency  to  this  defect)  it  is  a  safer  way  to  let  the  iron  development 
go  as  far  as  is  judged  safe,  then  first  wash  it  off,  and  then  hold 
up  to  the  light  and  examine.  Unless  the  picture  flashes  up  very 
suddenly  and  quickly,  it  is  safe  to  let  the  iron  development  do 
all  it  can,  before  washing.  Then  wash  off ;  if  the  negative  is 
found,  on  looking  through  it,  to  be  of  the  right  density,  all  is 
right.  If  not,  redevelop  with  pyrogallic  acid,  citric  acid,  and 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  319 

nitrate  of  silver,  taking  care  not  to  pour  on  the  solution  till 
every  atom  of  the  pyrogallic  acid  is  dissolved,  or  else  to  keep 
the  pyrogallic  acid  in  solution. 

When,  in  examining  a  negative,  it  is  found  that  along  the  edge 
which  was  farthest  from  the  operator  during  development  there 
are  streaks,  especially  branching  streaks,  the  operator  may  be 
pretty  sure  that  the  fault  arises  from  the  cause  here  described. 
And  if  he  doubts  it,  let  him  watch  the  plate  from  the  first  appli¬ 
cation  of  the  developer  to  its  complete  washing  off,  making  sure 
that  the  film  was  unbroken,  and  even  for  every  second  of  time. 
On  that  negative  the  streaks  will  be  absent,  always  supposing  it 
was  not  removed  too  soon  from  the  negative  bath.  (See  2.) 

Where  a  great  tendency  exists  in  the  negative  bath  to  form 
these  streaks,  it  is  well  to  agitate  the  plate,  during  immersion, 
from  side  to  side,  as  well  as  up  and  down.  In  fact,  this  last  is  a 
very  good  practice  for  habitual  adoption.  A  repellent  action  in 
the  film  may  arise  from  the  use  of  too  strong  alcohol  and  of  too 
much  ether  in  the  collodion.  Such  films  dry  rapidly,  do  not 
take  the  nitrate  bath  well,  and  repel  the  developer. 

Blanchard  has  remarked  that  the  keeping  qualities  of  plates 
may  be  greatly  increased  by  using  a  good  proportion  of  bromide, 
two  to  two  and  a  half  grains  to  the  ounce,  and  removing  from  the 
bath  as  soon  as  the  oily  lines  disappear — further,  hastening  that 
time  by  keeping  the  plate  constantly  in  motion  from  its  first 
entrance  into  the  bath.  In  this  way  some  of  the  bromide  may 
remain  undecomposed  by  the  silver  bath,  and,  decomposition 
continuing  after  the  removal  from  the  bath,  the  concentration  of 
the  nitrate  of  silver  and  its  consequent  evils  are  prevented.  He 
affirms  that  in  this  way  he  has  been  able  to  keep  a  plate  for  three 
hours.  Such  plates  must  be  developed  without  sulphate  of  copper 
in  the  developer,  or  brown  fogging  may  result. 

4.  Omitting  to  wipe  the  back ,  or  to  drain  sufficiently. 

5.  If  the  table  is  allowed  to  be  sloppy,  it  will  follow  that  the 
bottoms  of  the  developing  vessels  will  become  wet.  When  they 
are  turned  over  in  throwing  the  developer  on  the  plate,  there 
will  be  a  tendency  in  any  liquid  adhering  to  the  bottom  to  run 
along  the  side  and  mix  with  the  liquid  poured  out  from  the  vessel 
upon  the  plate.  Such  a  result  can  hardly  fail  to  produce  ugly  stains. 

6.  Inequalities  of  Temperature. — It  has  been  affirmed  that  when 
a  material  difference  in  the  temperature  of  the  bath  and  developer 
exists,  this  may  be  the  cause  of  streaks. 


320 


PHOTOGRAPHIC  MANIPULATIONS. 


7.  Streaks  Descending  more  or  less  Perpendicularly  from  the  Upper 
Part  of  the  Plate.  —  During  exposure  the  bath  solution  drains 
down  to  the  edge  of  the  plate,  and  tends  to  flow  thence  upon  the 
edge  of  the  dark  frame.  When  collected  there  in  a  drop,  it  easily 
rises  again  by  capillary  attraction  as  the  film  becomes  drier  by 
standing,  and  mounts  up  the  film  again,  so  giving  rise  to  a  streak. 
Eemedies:  1.  Wipe  out  the  dark  slide.  2.  Attach  a  piece  of 
blotting  board  to  the  edge  of  the  plate.  3.  Drain  better  after 
removing  from  the  bath  and  before  placing  in  the  dark  slide. 

Another  source  is  changing  the  position  of  the  plate  after  it 
has  drained  after  removal  from  the  sensitive  bath.  If  the  plate 
after  draining  be  turned  so  that  what  was  the  bottom  becomes  a 
side,  the  change  in  the  direction  of  the  currents  will  produce 
streaks  that  infallibly  ruin  the  negative. 

Neglect  to  keep  the  dark  slide  always  in  one  position  till  the 
plate  is  out  of  it  will  evidently  produce  the  same  result. 

In  a  word,  the  plate,  after  it  has  once  begun  to  drain ,  must  re¬ 
main  with  the  same  side  down  till,  by  the  completion  of  the 
development,  danger  is  ended. 

8.  Streaks  in  the  Direction  of  the  Dip  may  be  caused  by  the 
projection  of  the  dipper  that  holds  the  plate;  this  may  cause 
irregular  currents  over  the  plate  as  the  dipper  descends.  Where 
this  tendency  exists,  it  may  be  checked  by  lowering  the  plate 
very  gently  and  slowly  into  the  bath.  The  ether  in  the  collodion 
mixes  only  very  slowly  with  the  bath  solution,  and  by  rising  in 
currents  along  the  surface  of  the  plate  may  cause  streaks. 
Remedy :  move  the  plate  from  side  to  side  as  well  as  up  and 
down.  In  fact,  this  lateral  motion  is  well  to  practise  as  a  habit, 
together  with  the  regular  up  and  down  movement.  Scum  on  the 
surface  of  the  bath  may  also  cause  this  defect ;  a  piece  of  blot¬ 
ting-paper  drawn  lightly  over  the  surface  will  remove  the  scum. 

9.  Streaks  along  the  Border ,  or  working  in  from  the  Borders. — 1.  If 
the  film  becomes  loose  at  any  part  of  the  edge,  hyposulphite  may 
remain  under  it  and  escape  complete  removal  by  a  short  washing. 
If  then  the  plate  be  reinforced  with  pyro  and  silver,  brown  streaks 
may  result.  2.  Redeveloper  getting  under  the  film. 

10.  Parallel  Sets  of  Smeary  Streaks  or  Lines. — Cleaning  marks. 
Every  sort  of  cleaning  and  rubbing  upon  the  plate  leaves  invisi¬ 
ble  traces,  which  may  subsequently  come  out.  Whether  or  not 
they  will  do  so  depends  upon  various  influences:  If  the  develop¬ 
ment  is  much  pushed  ;  if  the  bath  or  other  chemicals  are  in  a 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  321 


condition  tending  slightly  to  fogginess,  the  tendency  to  abnormal 
deposit  will  be  apt  to  show  itself  by  first  depositing  on  the  clean¬ 
ing  marks.  Much  also  will  depend  upon  the  cleaning,  as,  if  the 
.plate  was  well  cleaned  first  in  the  bath;  if  the  chemicals  used  in 
cleaning  were  removed  or  not ;  if  the  paper  or  rags  used  in  rub¬ 
bing  were  clean  and  fresh,  or  old  and  soiled ;  if  rubbing  were  too 
hard. 

Or  the  operations  immediately  preceding  coating  may  have 
been  in  fault,  as  if  the  broad  soft  brush  used  for  removing  dust 
were  soiled  or  damp ;  or  if  there  were  any  deposit  of  dampness 
from  the  atmosphere  on  the  plate  when  brushed,  which  dampness 
would  by  the  brushing  be  drawn  into  streaks,  and,  moreover, 
soil  the  brush  and  spoil  also  the  next  following  plate.  Remedy, 
or,  rather,  prevention :  keep  the  plates  between  sheets  of  clean 
blotting-paper  in  a  tin  box,  and  the  brush  with  them,  removing 
each  plate  as  wanted  only.  Avoid  removing  the  plates  from  a 
cold  to  a  warmer  room  shortly  before  using. 


§  9. — Transparent  Spots  and  Pinholes. 

Pinholes . — Even  to  experienced  photographers  pinholes  are  a 
source  of  no  small  trouble.  They  consist  of  small  transparent 
dots  in  the  negative,  and  are  generally  occasioned  by  the  pre¬ 
sence  of  opaque  matter  adhering  to  the  plate  and  interposing 
between  the  light  and  the  plate.  During  the  subsequent  opera¬ 
tions  these  are  removed,  and  the  portion  of  iodide  beneath  having 
been  sheltered  from  the  light,  dissolves  out  in  the  hyposulphite. 
These  pinholes  have  been  traced  to  the  following  sources: — 

1.  Dust  in  the  bath — remedy,  filtration. 

2.  Crystals  of  iodo-nitrate  of  silver  floating  in  the  bath. 

Iodide  of  silver  is  capable  of  dissolving  in  nitrate  of  silver, 

and  certain  conditions  of  the  bath  appear  greatly  to  favor  this 
solution.  A  new  bath  may  be  pretty  thoroughly  saturated  with 
iodide  of  silver  and  yet  give  no  pinholes,  whereas  an  old  bath 
can  at  times  scarcely  be  kept  free  from  them,  and,  even  if  removed 
by  appropriate  treatment,  they  quickly  return.  The  treatment 
is  as  follows  : — 

.  a.  Add  a  few  drops  of  solution  of  sal  ammoniac,  and  filter. 
This  is  a  palliative ;  the  pinholes  mostly  soon  return. 

b.  Take  one-half  the  bath,  and  pour  it  slowly  into  a  quantity  of 
water  about  its  own  bulk  (do  not  reverse  this),  that  is,  if  you  have 


322 


PHOTOGRAPHIC  MANIPULATIONS. 


a  thirty-ounce  bath,  pour  fifteen  ounces  of  it  into  fifteen  ounces 
of  water,  and  filter.  Add  the  rest  of  the  bath,  without  filtration, 
and  then  add  forty  grains  of  nitrate  of  silver  for  each  ounce  of 
water  added,  unless  the  bath  was  at  the  time  impoverished,  in 
which  case,  of  course,  the  addition  must  be  larger.  Sun  it,  and 
filter. 

In  some  states  of  the  bath  this  treatment  will  give  effectual 
relief  for  a  considerable  time.  But  an  old  bath  seems  to  acquire 
an  increasing  tendency  to  dissolve  out  the  iodide  of  silver  from 
the  plate  and  precipitate  it  in  these  irritating  crystals.  When  it 
is  found  that  this  tendency  to  recur  is  obstinate,  it  is  better  to — 

c.  Evaporate  the  bath  to  dryness  in  a  porcelain  basin ;  and  if, 
after  going  down  to  thorough  dryness,  the  heat  be  raised  gradually 
till  the  saline  mass  fuses,  it  will  be  so  much  the  better.  But 
even  evaporation  to  dryness,  without  fusing,  will  be  a  valuable 
help.  For  the  presence  of  alcohol  in  the  bath,  introduced  by  the 
collodion  on  the  plates,  seems  greatly  to  facilitate  the  solution  of 
the  iodide  and  the  formation  of  iodo-nitrate ;  the  dry  mass  when 
dissolved  in  water  gives  a  milky  liquid,  by  reason  of  the  iodide 
now  become  insoluble,  and  which  is  got  rid  of  by  filtration.  If 
the  heat  have  been  raised  to  the  fusing  point,  the  riddance  of  the 
iodide  seems  to  be  still  more  complete;  the  fused  nitrate  may  be 
used  as  new,  remembering,  however,  that  it  contains  alkaline 
nitrate,  and  is  not  all  silver-nitrate,  more,  therefore  (if  weighed), 
will  be  needed  than  of  unmixed  nitrate  of  silver.  Probably  the 
bath  will  not  require  acidulating,  and  acid  should  not  be  added 
till  it  is  found  that  a  trial  plate  is  fogged  without. 

3.  Another  source  has  lately  been  brought  forward  as  causing 
pinholes,  viz.,  the  presence  of  sulphuric  acid,  or  sulphates,  in 
the  water.  Trouble  from  this  source  is,  however,  rare. 

4.  Some  hold  that  acidulating  with  acetic  acid  gradually  leads 
to  pinholes  by  reason  of  formation  of  acetate  of  silver. 

5.  If  the  salting  in  the  collodion  is  not  thoroughly  dissolved, 
it  may  remain  as  a  fine  powder  in  suspension,  and  every  grain  of 
it  may  be  expected  to  cause  an  insensitive  spot,  which  may  be  much 
larger  than  the  grain  itself,  as  its  influence  will  extend  around. 
The  bromides  are  less  soluble  in  alcohol  and  ether  than  the 
iodides,  especially  the  bromide  of  potassium  ;  and  this  substance, 
even  if  not  introduced  as  such  into  the  collodion,  will  always  be 
formed  if  iodide  of  potassium  is  used  in  connection  with  any 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  323 

bromide.  The  stronger  and  better  the  alcohol  and  ether  the 
more  liable  they  will  be  to  this  trouble. 

Therefore,  if  it  be  considered  essential  to  introduce  a  potassium 
salt,  it  will  be  necessary  to  select  a  cotton  which  will  work  well 
with  alcohol  not  too  high.  In  this  respect  cottons  differ  very 
widely,  some  requiring  the  strongest  solvents,  and  some  working 
with  quite  watery  ones.  Cotton  having  this  last  quality  will  be 
appropriate  for  ambrotypes  and  ferrotypes,  as  it  is  for  such  that 
potassium  is  commonly  introduced  into  the  collodion. 

As  a  remedy,  introduce  a  few  drops  of  water,  shake  thoroughly, 
set  in  not  too  cool  a  place,  and  at  the  end  of  twenty-four  hours 
filter  through  a  close  filter. 

Or  dilute  the  collodion  with  a  little  plain  collodion,  thus  in¬ 
creasing  its  solvent  powers.  According  to  V.  Blanchard,  this  is 
very  effective,  when,  after  working  for  some  time  well,  one  is 
suddenly  troubled  with  pinholes.  The  explanation  of  the  remedy 
is  evident. 

Continual  moving  of  the  plate  whilst  in  the  nitrate  bath,  with¬ 
out  ceasing  till  it  is  withdrawn,  is  also  recommended  by  the  same 
photographer.  ^ 

Large  Clear  or  Hazy  Spots. — 1.  When  the  developer  is  not  swept 
along  the  upper  edge  as  here  recommended,  but  poured  over  the 
plate  in  the  same  manner  as  the  collodion  (as  is  practised  by  some 
operators),  a  transparent  spot,  half  an  inch  or  more  in  diameter, 
is  very  apt  to  be  formed  unless  the  operator  rapidly  moves  the 
hand  which  pours  on  the  developer.  This  spot  is  caused  by  the 
washing  away  of  the  bath  solution,  so  that  when  development 
sets  in,  that  part  of  the  film  is  deficient  in  free  nitrate  of  silver, 
and  is  proportionally  weaker  in  effect.  2.  Collodion  poured  too 
suddenly  back  into  the  vial,  making  an  irregular  film.  3.  Bad 
cotton,  which  does  not  thoroughly  dissolve  in  the  fluid,  and  which 
has  not  been  properly  filtered.  4.  Bad  collodion,  too  thick,  or 
with  alcohol  and  ether  badly  proportioned  (i.  e.,  alcohol  should  be 
J-  to  J,  ether  J  to  §).  5.  A  new  bath,  not  saturated  with  iodide 

of  silver,  will  corrode  the  first  plates.  6.  An  over-strong  bath 
may  produce  the  like  effect.  7.  Keeping  too  long  before  develop¬ 
ing  may  produce  roundish  hazy  spots,  especially  when  the  bath 
is  acidulated  with  nitric  acid.  Apparently,  this  happens  most 
easily  in  hot  weather,  when  the  evaporation  is  most  rapid.  The 
bath  solution  becomes  concentrated  and  dissolves  out  portions  of 
the  film.  It  does  not  act  equally,  because  as  it  evaporates  it  has 


324 


PHOTOGRAPHIC  MANIPULATION'S. 


a  tendency  to  collect  in  drops  on  the  surface.  8.  Fragments  of 
collodion  (generally  from  the  back  of  the  plate)  in  the  bath. 

As  mentioned  elsewhere,  small  transparent  spots  in  a  negative 
should  always  be  touched  out  with  opaque  color.  This  causes 
them  to  print  white  spots  in  the  print,  which  are  easily  retouched 
and  brought  up  to  the  surrounding  shade.  But  a  transparent 
spot  prints  dead  black,  and  this  is  much  more  difficult  to  manage 
and  the  blemish  is  never  so  well  concealed. 

Rings. — If  the  collodion  bottle  be  held  too  high  above  the  plate  in 
eollodionizing,  rings  may  appear  in  the  development. 


§  10. — Comets  and  other  Opaque  Spots. 

The  name  comet  (A,  A',  Fig.  127)  very  aptly  designates  those 
larger  or  smaller  spots  with  tails,  opaque  in  the  negative  and 
showing  more  or  less  white  if  printed,  so 
that  unless  but  a  few  prints  are  wanted, 
and  the  photographer  is  willing  to  touch 
out  the  comet’s  mark,  the  negative  may 
generally  be  considered  as  worthless. 

The  heads  of  these  comets  mostly  are 
towards  the  direction  from  which  the  de¬ 
veloper  came,  and  the  tails  pointing  to 
the  side  on  which  it  ran  off.  They  may 
be  caused  by  anything  that  forms  reduc¬ 
tion  at  some  chance  point.  A  fragment  of  undissolved  pyrogallic 
acid,  unnltered  solutions  of  sulphate  of  iron,  organic  dust  on  the 
plate,  or  in  the  sensitizing  bath,  or  floating  on  its  surface,  any  of 
these  causes  may  produce  comets.  Their  appearance  may  be 
taken  as  a  plain  indication  that  one  or  more  of  the  solutions 
worked  with  wants  filtering. 

Or,  suppose  that  hyposulphite  is  spilt  about  the  room.  The 
grating  of  the  feet  on  the  floor  or  carpet  grinds  off  dust  which  is 
charged  with  hyposulphite.  If  the  glass  be  rubbed  immediately 
before  coating,  it  becomes  electrical,  and  every  floating  mote  near 
it  is  drawn  to  it.  These  are  imbedded  in  the  collodion,  and  on 
plunging  the  plate  in  the  bath,  they  become  centres  of  reduction. 
Sometimes  these  are  even  observable  as  dark  spots  on  removing 
the  plate  from  the  bath.  But  if  the  proportion  of  hyposulphite 


Fig.  127. 


B,  Development  stains. 


FAILURES  IN'  PHOTOGRAPHIC  OPERATIONS.  325 

is  infinitesimal,  jet  they  may  escape  attention  on  withdrawing 
the  plate,  and  cause  comets. 

If  this  dust  is  about  the  room,  it  can  scarcely  but  get  into  the 
dark  slide,  and  then  in  moving,  especially  if  roughly  moved,  it 
may  be  transferred  to  the  plate,  and  lead  to  comets. 

Metallic  hinges  to  the  dark  slide  will  sometimes  grind  off  par¬ 
ticles  of  metal  which  may  be  transferred  to  the  plate.  Each  be¬ 
comes  a  centre  of  reduction,  and  must  lead  to  the  formation  of 
a  spot  of  some  sort,  probably  a  comet. 

Imperfectly  filtered  collodion  may  give  rise  to  opaque  spots. 
Also,  neglect  to  wipe  thoroughly  the  lip  of  the  vessel  from  which 
the  collodion  is  poured. 

Where  any  cause  of  comets  is  present,  a  strong  developer  tends 
naturally  to  aggravate  the  evil.  A  rather  acid  developer  is  the 
easiest  worked  with,  but  does  not  give  as  fine  results,  viz.,  as 
much  transparency  of  shadow.  At  the  same  time,  it  diminishes 
the  tendency  somewhat  to  stains,  and  helps  detail  in  high  lights, 
such  as  white  dresses  in  portraiture,  or  a  strongly  illuminated 
distance  in  landscapes ;  also  fine  lines  in  copying  line  engravings 
(not  mezzotints,  photographs,  lithographs,  or  India-ink  drawings), 
for  all  of  which  a  well  balanced,  i.  e.f  moderately  acidified,  deve¬ 
loper  is  needed.  Finally,  the  developer,  if  not  kept  in  continual 
motion  over  the  plate,  may  allow  particles  of  metallic  silver  to 
fall,  which  presently  become  nuclei  of  development. 

Opaque  spots  may  be  caused  by  a  lumpiness  of  the  film,  arising 
from  some  insoluble  substance  in  the  collodion.  Often  minute 
fragments  of  dried  collodion  are  carried  over  from  the  neck  of 
the  pourer,  by  neglect  to  wipe  after  every  pouring.  The  least 
dust  in  the  collodion  will  cause  these  spots ;  after  it  is  examined 
with  a  lens  they  will  be  found  to  be  caused  by  a  minute  fibre  of 
wool :  it  is  surprising  how  much  thickening  a  single  fibre  may 
cause  in  this  way.  These  fibres  may  get  into  open  vessels  of 
collodion,  or  may  have  settled  into  vials  or  pourers  before  they 
were  filled  with  collodion.  Or  (as  this  is  the  commonest  case) 
they  have  settled  on  the  plate  itself ,  either  from  neglect  to  brush 
it  off,  or  from  doing  so  too  long  before  coating,  so  that  dust  set¬ 
tles  on  it  between  times.  Dust  is  a  foe  to  many  photographic 
operators,  and  most  of  all  to  albumenized  plates ,  and  every  care 
should  be  taken  to  exclude  it. 


326 


PHOTOGRAPHIC  MANIPULATIONS. 


§  11. — Lines. 

1.  A  pause ,  "however  momentary,  in  the  immersion  of  the  plate, 
produces  a  line,  generally  as  thin  as  a  hair,  at  the  place  where 

the  pause  took  place.  With  a  vertical  bath, 
such  a  line  is  necessarily  a  straight,  or  nearly 
straight,  one  (see  A,  Fig.  128).  With  a  hori¬ 
zontal  bath  the  most  curious  curves  and  sinu¬ 
ous  lines  are  seen  (B  B,  same  figure).  If  the 
horizontal  bath  has  not  been  deep  enough  to 
cover  the  plate  with  a  single  wave,  but  pauses 
for  a  fraction  of  a  second,  the  mark  of  that 
pause  will  inevitably  appear  in  the  develop¬ 
ment,  and  the  negative  is  of  course  ruined- 
Bemedy :  with  a  vertical  bath,  immerse  the  plate  with  perfect 
regularity.  With  a  horizontal  bath,  have  plenty  of  solution, 
raise  the  bath  at  one  end,  place  the  plate  in  at  that  end,  raised  so 
high  that  the  solution  leaves  it,  and  then,  at  the  same  time,  lower 
that  end  and  let  the  other  end  of  the  plate  fall  gently  in. 

2.  Wavy  Lines  at  Edges. — Developer  too  small  in  quantity,  or 
too  slowly  applied,  especially  where  the  plate  has  been  kept 
some  time  after  leaving  the  bath. 

3.  Fine  Parallel  Vertical  Lines  in  Direction  of  Dip. — The  writer 
has  seen  this  result  from  sulphate  of  iron  in  the  silver  bath, 
thousands  of  such  lines  being  thus  produced. 

4.  Sinuous  Lines  over  the  Plate. — If  the  film  be  of  a  very  repel¬ 
lent  nature,  the  bath  solution  may,  instead  of  remaining  as  an  even 
film,  gradually  collect  in  oily  lines,  or  the  plate  may  by  inatten¬ 
tion  have  been  removed  from  the  bath  with  these  lines  actually 
upon  it.  This  repellent  character  (see  p.  318)  may  come  from 

various  sources:  1.  Bad  quality  of 
cotton.  2.  Alcohol  and  ether  too  high; 
add  a  very  little  water.  3.  A  horny 
and  contractile  collodion. 

5.  Parallel  Lines ,  darker  than  the  Ad¬ 
joining  Parts. — When  a  plate  which  has 
not  been  very  well  cleaned  is  subjected 
to  a  long  and  severe  development, 
traces  of  the  lines  of  the  cleaning  will 
be  forced  out  in  the  development.  (See  Fig.  129.)  Sometimes 
these  are  simply  parallel  lines  as  at  A,  sometimes  they  show 


Fig.  129. 


Fig.  128. 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  827 


angles  as  at  B.  These  angles  are  where  the  direction  of  the 
hand  was  changed  in  the  deaning.  Bemedy:  Clean  better  and 
rub  longer. 


§  12. — Stains  and  Surface  Markings. 

Marbled  Stains . — 11  Oyster-shell”  stains  of  reduced  silver  (also 
called  “  matt  silver  stains”),  with  a  gray  metallic  surface  and  in 
curious  curved  and  arabesque  patterns,  occasionally  make  their 
appearance.  They  are  exceedingly  peculiar  and  unlike  any  other 
stains,  and  have  occasioned  much  speculation  and  discussion. 
They  come  from  too  long  an  interval  between  collodionizing  and 
plunging  into  nitrate  bath,  too  strong  a  de¬ 
veloper,  or  too  long  a  development,  espe¬ 
cially  with  sulphate  of  iron. 

The  longer  a  plate  is  required  to  wait  be¬ 
tween  sensitizing  and  development  the  worse 
will  be  these  stains.  Plates  which  when  de¬ 
veloped  within  five  or  ten  minutes  after 
withdrawal  from  the  nitrate  bath  are  per¬ 
fectly  clean,  will  sometimes,  if  kept  for 
half  an  hour,  show  abundance  of  these 
stains.  Some  operators  find  them  come  on  “Marbled”  or  “oyster- 
large  plates  when  they  do  not  on  small.  shell”  surface  stains. 

Or  they  may  be  caused  by  neglect  to  wipe  the  back  of  the 
plate,  or  to  let  it  drain  a  sufficient  time  before  putting  it  into  the 
dark  slide.  In  these  ways  bath  solution  may  run  down  to  the 
bottom  of  the  back,  and  work  round  to  the  collodion  film.  They 
may  also  arise  from  scum  on  the  surface  of  the  bath,  which  is 
taken  up  by  the  plate,  and  is  subsequently  developed  by  the 
action  of  the  developer.  According  to  some  reliable  photo¬ 
graphers,  iodide  of  ammonium  in  the  collodion  tends  strongly  to 
the  formation  of  this  species  of  stains.  They  usually,  however, 
indicate  too  long  an  interval  between  collodionizing  and  de¬ 
velopment.  Bemedy:  Let  the  operations  follow  each  other  more 
rapidly.  If  this  cannot  be,  use  more  bromide,  agitate  the  plate 
the  whole  time  that  it  is  in  the  bath,  and  remove  it  from  the 
bath  the  moment  the  oily  lines  disappear. 

In  very  hot  weather  these  stains  will  show  themselves  upon 
plates  otherwise  every  way  perfect,  even  with  a  bath  quite  suffi¬ 
ciently  acidulated,  and  with  a  collodion  containing  iodine.  The 


Fig.  130. 


328 


PHOTOGRAPHIC  MANIPULATIONS. 


longer  the  interval  between  the  operations  the  larger  and  more 
numerous  they  are.  They  appear  to  depend  upon  the  drying  of 
the  collodion  film  on  the  surface,  and  upon  a  partial  return  by 
capillary  action  of  silver  solution  which  has  drained  down  to 
the  corner.  Silver  solution  which  has  once  touched  the  holder 
becomes  sufficiently  changed  to  throw  down  its  metal  much  more 
rapidly  under  the  developer. 

The  writer  has  devised  and  used  the  following  remedy  with 
great  advantage.  A  piece  of  thick  blotting  pad  is  cut  to  the 
length  of  the  lower  edge  of  the  plate,  and  made  about  an  inch 
and  a  half  wide.  A  very  narrow  portion,  say  an  eighth  of  an 
inch  or  less  in  width,  is  bent  over  to  a  right  angle  for  the  whole 
length,  and  after  the  plate  is  put  into  the  holder  it  is  raised  up  a 
little,  and  this  bent  edge  is  pushed  in  between  the  plate  and  the 
corners.  Thus  the  edge  (not  the  face)  of  the  glass  and  of  the 
collodion  film  touch  this  blotting-paper  over  the  whole  length, 
and  whatever  solution  drains  down  is  absorbed  by  the  blotting 
pad,  and  is  drawn  round  by  it  to  the  back.  This  remedy  was 
found  very  valuable. 

Or  it  is  advisable,  when  such  a  tendency  appears  :  1.  To  care¬ 
fully  wipe  out  the  dark  slide  with  a  wet  cloth,  in  order  super¬ 
ficially  to  wet  the  surface.  2.  To  place  a  piece  of  thick  blotting- 
paper  on  the  back,  as  just  explained.  3.  To  diminish  the  inter¬ 
vals  before  the  development  as  much  as  possible.  4.  Tf  neces¬ 
sary,  to  roll  the  dark  slide  in  a  damp  cloth.  The  first  remedy  is, 
however,  by  far  the  best.  (See  also  p.  344.) 

It  has  been  stated  that  these  oyster-shell  markings  may  arise 
from  something  in  the  acetic  acid  used  in  the  developer,  and  that 
they  have  instantly  disappeared  by  changing  the  specimen  of 
acid  used.  Others,  again,  have  attributed  them  to  the  greater 
thickness  of  the  film  at  the  corner  where  poured  off,  so  that  this 
portion,  drying  more  slowly,  is  exposed  to  become  loose  in  the 
nitrate  bath,  and  to  retain  some  bath  solution  beneath  it. 

Stains  of  this  sort  are  very  superficial,  and,  by  dexterous 
manipulation,  may  often  be  entirely  removed.  The  surface  of  the 
collodion  is  to  be  thoroughly  wetted,  best  with  alcohol,  and  a  piece 
of  very  soft  paper  is  well  moistened,  and  a  point  of  it  carefully  and 
repeatedly  drawn  over  the  stain.  Unless  the  pressure  is  exceed¬ 
ingly  gentle,  the  film  gives  way,  but  when  care  is  taken,  the  stains 
disappear  wonderfully.  The  writer  has  seen  a  third  of  the  surface 
of  a  negative  covered  with  these  stains,  and  yet  has  succeeded  in 


FAILURES  JN  PHOTOGRAPHIC  OPERATIONS.  329 

getting  rid  of  them  with  care  and  patience.  A  kind  of  very  thin 
brown  paper,  made  of  jute,  is  that  which  has  been  found  to 
answer  best.  It  becomes  exceedingly  tender  when  wet.  The 
operation  is  best  performed  after  fixing. 

Brown  Stains. — If  it  is  desired  to  reinforce  after  fixing  with 
hyposulphite,  careful  washing  is  necessary  before  the  pyro  and 
silver  are  applied ;  if  traces  of  hypo  remain  in  or  under  the 
film,  a  brown  stain  of  sulphide  of  silver  makes  its  appearance 
the  instant  the  redeveloping  solution  is  put  on  the  plate. 

These  stains  are  also  said  to  arise  from  using  pyrogallic  acid 
with  too  little  acetic  acid,  when  the  water  is  hard  (limestone 
water),  and  sometimes  from  white  light  admitted  to  the  dark 
room.  Redeveloper  getting  under  the  film  will  stain  brown. 

If  the  collodion  be  alkaline  it  will  be  highly  sensitive,  and 
tend  to  give  flat  images,  and  at  the  same  time  to  stain  with  the 
slightest  cause.  The  least  impurity  on  the  glass,  the  least  mis¬ 
management  of  development,  may  be  expected  to  spoil  the  plate. 

Neglect  to  keep  the  plate-holder  clean  will  give  rise  to  very 
troublesome  markings.  The  all  but  universal  use  of  glass  corners 
in  the  slides  has  largely  diminished  the  injuries  from  dirty  plate- 
holders,  nevertheless  it  is  still  advisable  to  be  on  the  safe  side. 
Paraffining  the  slide,  or,  what  is  easier,  rubbing  it  well  with  lard, 
prevents  the  soaking  in  of  droppings  and  drainings,  and  renders 
the  slides  more  easy  to  keep  clean. 

It  seems  scarcely  necessary  to  say  that  any  solution  left  upon 
the  glass  corners  for  want  of  wiping  is  transferred  to  the  next 
plate,  and  may  show  itself  in  the  production  of  different  sorts  of 
stains  according  to  the  condition  of  the  chemicals. 

Irregular  Markings  are  said,  in  some  cases,  to  arise  from  the 
use  of  too  strong  alcohol  and  ether  in  the  collodion.  Mr.  Terry 
mentions  a  case  as  occurring  in  a  gallery  in  which  not  a  perfect 
negative  had  been  made  in  a  week,  and  where  the  trouble  was  at 
once  removed  by  adding  a  few  drops  of  water  to  the  collodion. 
It  had  been  made  by  the  photographer  himself ;  absolute  alcohol 
was  used  instead  of  95  per  cent.1 

1  Really  absolute  alcohol  is  rarely  to  be  met  with  in  commerce.  The  differ¬ 
ence  between  95  per  cent,  alcohol  and  absolute  is  oyer  25  drops  of  water  to  the 
fluidounce,  rather  more  than  5  drops  to  each  hundred.  It  will  thus  appear 
how  important  it  is  to  understand  the  exact  strength  of  the  materials  used. 

22 


330 


PHOTOGRAPHIC  MANIPULATIONS. 


13. — Faults  in  Fixing. 


Fig.  131. 


Feathery  Markings  over  the  Plate. — Yellowish  feathery  markings 
are  owing  to  insufficient  fixing.  These  may  appear  at  any  part 
of  the  plate,  most  frequently,  however,  at 
the  corner  at  which  the  collodion  was 
poured  off.  At  times  a  yellow  shade  is  left 
over  the  whole  plate ;  this  indicates  a  still 
more  imperfect  fixing. 

When  this  fault  is  not  noticed  until  the 
plate  has  been  washed  and  dried,  particular 
care  is  necessary ;  for  plates  thrown  into 
hyposulphite  a  second  time  are  almost  cer¬ 
tain  to  loosen  in  the  film,  or  to  split  in  some 
part  of  the  operation,  either  in  the  fixing,  or 
washing,  or  the  drying ;  therefore,  the  best 
precaution  is  to  take  a  grain  solution  of 
India-rubber  in  benzole,  to  pour  out  an  ounce  or  two  of  it  into  a 
pan,  and  tilt  the  pan  upward  at  one  side,  so  that  the  solution  may 
lie  in  the  angle  opposite.  We  thus  have  a  pool  the  length  of  the 
pan,  and  about  one-fourth  of  an  inch  deep  in  the  middle.  The 
four  edges  of  the  plate  are  to  be  plunged  in  this  successively, 
giving  each  a  full  minute  to  allow  the  varnish  to  soak  in,  and 
also  to  allow  the  previous  side  to  drain  and  dry  before  it  becomes 
the  top.  The  plate  thus  cemented  fast  at  the  edges,  will  stand 
the  necessary  treatment  without  difficulty.  After  refixing  and 
washing,  coat  with  gum-water  or  dilute  albumen,  dry  and 
varnish. 

Image  Weakens  too  much  in  Fixing. — The  fixing  bath  may  be 
too  strong  and  need  weakening.  The  result  may  also  come  from 
too  vjeak  a  negative  bath ,  used  too  long  without  strengthening  up. 
The  iodide  of  silver  is  then  formed  too  much  on  the  surface  of, 
instead  of  within,  the  film.  Or  the  development  may  have  not 
been  continued  sufficiently  long.  It  should  be  borne  in  mind 
that  the  portions  of  the  image  formed  by  redevelopment  are  less 
easily  attacked  by  the  fixing  bath  than  those  formed  in  the  first 
development. 


§  14. — Faults  in  Varnishing. 

Drying  Dead. — This  may  result  from  one  or  more  of  three  dis¬ 
tinct  causes. 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  331 

1.  Want  of  dryness  of  the  film.  As  water  curdles  varnish  by 
precipitating  the  resin,  so  any  dampness  in  the  film  will  produce 
a  similar  effect.  Surface  drying  is  insufficient.  The  film  must 
be  dry  clear  through  to  the  glass.  By  standing  for  a  day,  the 
film  dries  sufficiently  in  dry  weather,  but  a  damp  atmosphere, 
even  in  sunny  weather,  will  dampen  films  to  that  extent  (even  if 
they  were  previously  dry)  that  the  varnishing  may  be  affected. 
As  a  getieral  thing,  it  is  best  to  varnish  in  dry  weather  only ;  but 
if  it  is  to  be  done  in  damp  weather,  artificial  heat  must  be  used. 
Merely  warming  the  plate  will  not  dry  it;  it  must  be  kept  warm 
for  some  little  time. 

2.  Insufficient  penetration.  Varnishes  penetrate  rather  more 
slowly  than  many  persons  imagine,  and  if  poured  off  before  pene¬ 
tration  has  taken  place,  the  varnish  continues  to  soak  in,  and 
thus  the  upper  portion  has  not  enough  left  to  give  it  a  glossy 
surface.  After  the  plate  has  been  completely  covered,  the  writer 
advises  to  count  ten  or  twelve  seconds  before  beginning  to  pour  off. 

3.  Insufficient  heat.  Some  varnishes  require  more  heat  than 
others,  and  if  enough  is  not  applied  they  dry  dead.  Most  var¬ 
nishes  require  heat  both  before  and  after  applying. 

Remedy  for  Deadness. — Flow  with  alcohol  (see  below). 

Ridges. — If  the  pool  of  varnish  be  allowed  to  stop  too  long  in 
any  position,  it  dries  at  the  edge  and  makes  a  ridge,  and  the 
tendency  will  always  be  greater  in  proportion  as  the  plate  is 
hotter.  If,  while  varnishing,  the  photographer  sees  that  he  has 
made  a  ridge,  he  can,  if  it  is  not  a  bad  one,  get  rid  of  it  by 
pouring  an  abundant  supply  of  varnish  on,  and  letting  it  remain 
longer  on  the  plate  than  usual. 

Different  varnishes  work  differently,  and  sometimes  the  mere 
change  from  one  that  the  photographer  is  accustomed  to,  to  an¬ 
other  equally  good,  but  different,  will  cause  him  to  make  ridges. 

When,  after  drying  a  negative  by  heat,  the  varnish  is  found  to 
have  made  a  ridge  across  the  film  likely  to  show  in  the  printing, 
or  has  dried  sufficiently  dead  to  unfavorably  affect  the  print,  it 
is  not  necessary  to  remove  the  whole  of  the  varnish.  The  writer 
simply  flows  the  negative  over  with  95  per  cent,  alcohol,  letting 
it  stand  on  the  film  for  two  or  three  seconds,  and  pours  off;  then 
warms  the  plate  and  applies  another  coat  of  varnish.  For  this 
last  varnishing  it  is  best  to  use  a  thinner  varnish,  lest  the  coat 
become  too  thick.  Therefore  dilute  the  varnish  (if  a  spirit  var- 


332 


PHOTOGRAPHIC  MANIPULATIONS. 


nish,  and  the  writer  advises  to  use  none  other)  with  an  equal  bulk 
of  alcohol.  The  same  remedy  applies  for  drying  dead. 

Scaling  Off  after  a  Lapse  of  Time. — This  arises  from  leaving  the 
varnish  on  too  short  a  time  before  pouring  off.  Those  places 
where  it  has  not  soaked  through  to  the  glass  will  always  be  liable 
to  scale  off.  Or  if  the  plate  has  been  badly  washed  and  hypo¬ 
sulphite  crystallizes  under  the  film.  Exposure  of  the  negative  to 
damp  atmosphere.  Great  changes  of  atmosphere,  as  if  the  room 
is  allowed  to  frequently  become  very  cold  and  then  is  strongly 
heated.  Bad  varnish,  containing  no  essential  oil  (oil  of  lavender, 
etc.).  Coating  with  gum-water  before  varnishing,  in  order  to 
prevent  splitting  in  drying. 

Any  varnish  which  tends  in  the  least  degree  to  show  this 
defect  should  be  rejected  without  hesitation.  Under  the  head  of 
varnishes,  will  be  given  further  on  several  formulas  for  varnishes 
which  will  resist  the  action  of  moisture  so  completely  that  nega¬ 
tives  varnished  with  them  may  lie  under  water  for  many  weeks 
without  injury  of  any  sort. 

Dissolving  of  the  Image  in  Varnishing. — The  cotton  too  soluble 
in  alcohol  alone  without  ether.  Alcohol  in  the  varnish  too 
strong.  Bemedy  :  add  a  little  water ;  shake  well,  and  if  not  quite 
bright,  filter  through  paper ;  or  use  a  benzole  varnish.  This 
trouble  comes  chiefly  with  pyroxyline  made  at  a  low  temperature 
with  weak  acids ;  and  as,  of  late  years,  the  tendency  has  been  to 
strengthen  the  acids,  and  counterbalance  this  by  raising  the  tem¬ 
perature,  the  tendency  to  dissolve  in  varnishing  occurs  less  fre¬ 
quently  than  formerly. 

Honeycomb  Cracks. — The  varnish  after  a  time  rises  in  ridges, 
and  finally  parts.  Cause :  insufficient  removal  of  hyposulphite  in 
washing.  If  attended  to  in  time,  this  may  be  remedied.  Alcohol 
is  put  into  a  pan,  and  the  plate  put  over  it,  face  down,  until  the 
varnish  softens  and  returns  to  its  position ;  or  the  plate  is  simply 
flowed  over  with  hot  alcohol.  The  ridges  sink  down  sufficiently 
not  to  affect  the  printing. 

Parallel  Lines  running  diagojially  down  the  Plate. — Certain  var¬ 
nishes,  and  especially  thick  ones,  require  to  be  rocked  whilst 
draining  and  drying,  for  want  of  which  this  trouble  may  arise. 

Scratching  in  Handling. — Too  thin  a  varnish  will  not  afford  an 
adequate  protection  to  the  film,  which  may  thus  be  unable  to 
stand  ordinary  wear.  A  habit  of  thinning  the  varnish  with 
.alcohol  may  easily  be  carried  to  excess,  and  lead  to  this  trouble. 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  333 

Generally  speaking,  the  solid  gum  should  be  in  the  proportion  of 
one  ounce  to  seven  fluidounces  of  alcohol,  with  some  essential  oil 
to  prevent  cracking. 

A  more  common  source  of  this  trouble  lies  in  the  use  of  var¬ 
nishes  made  with  too  soft  gums.  Lac  is  liable  to  this  objection. 
The  sandarac  varnish,  for  which  a  formula  will  be  given  in  the 
chapter  on  varnishes,  gives  an  extremely  strong,  hard  coat. 

Specks  and  Irregularities  on  the  Surface. — Although  the  var¬ 
nish  have  been  perfectly  clean  and  bright,  and  although  the 
negative  may  have  been  carefully  brushed  off  immediately  before 
applying  the  varnish,  it  will  often  happen  that  there  will  be 
specks  and  irregularities.  Examined  with  a  lens,  these  will 
mostly  'show  a  filament  of  wool  (from  abrasion  of  clothes  or 
carpets)  in  the  centre  as  the  cause.  The  air  is  mostly  much  fuller 
of  dust  than  we  imagine,  and  these  filaments  will  settle  on  the 
plate  even  in  the  few  seconds  between  brushing  and  coating. 


I  15. — Miscellaneous. 

1.  No  Image  at  all. — In  copying  by  a  bad  light,  if  too  small  a 
diaphragm  be  used,  and  a  much  too  short  exposure  be  given,  with 
insensitive  chemicals,  the  developer  may  fail  to  bring  anything 
out.  A  very  exceptional  case.  In  some  states  of  the  negative 
both  cadmium  collodions  will  fail  to  give  any  image  at  all,  when 
the  mere  substitution  of  a  collodion  made  chiefly  with  salts  of 
ammonium  wili  lead  to  good  results  immediately  (p.  136). 

2.  Insensitiveness  arises  either  from  too  acid  a  condition  of  the 
negative  bath  or  from  the  use  of  too  old  acid,  or  dark  collodion. 
If  from  the  latter  cause,  it  will  be  at  once  removed  by  substi¬ 
tuting  a  collodion  in  good  condition.  And  if  the  old  collodion 
be  not  too  defective,  it  may  be  used  up  by  mixing  with  some 
that  has  been  very  newly  prepared  of  thoroughly  neutral  mate¬ 
rials,  preferably  with  cadmium  salts  only,  and  which  by  the 
admixture  of  an  older  collodion  will  at  once  pass  into  good  con¬ 
dition. 

It  is  usually  collodions  made  with  alkalies  that  become  insen¬ 
sitive.  Cadmium  collodions  will  keep  in  cool  places  for  several 
years. 

As  to  the  proportions  in  which  to  mix  new  and  old  collodions, 
one  part  of  old  may  be  added  to  three,  four,  or  five  of  new,  ac- 


334 


PHOTOGRAPHIC  MANIPULATIONS. 


cording  to  circumstances.  If  the  old  collodion  be  quite  dark,  it 
will  hardly  be  safe  to  add  in  larger  proportion  than  five.  Over¬ 
acidity  of  the  bath  is  generally  the  result  of  tampering  with  it — 
as  a  general  rule,  after  your  bath  is  once  rightly  made,  ascribe 
all  troubles  to  anything  else,  and  apply  no  remedies  to  it,  until 
it  is  certain  that  it  is  in  fault.  If  too  much  acid  has  been 
added,  by  mistake,  in  making  it,  bicarbonate  of  sodium  may  be 
added  very  cautiously  until  a  precipitate  falls,  then  filter  and 
acidulate  again. 

An  old  bath,  choked  with  organic  matter,  may  cause  insensi¬ 
tiveness. 

3.  The  Film ,  after  Fixing  with  Cyanide ,  shows  a  Bluish  Color. — 
Insufficient  washing  off  after  development,  so  that  iron  salt  re¬ 
mains  on  the  plate. 

4.  Want  of  Adherence. — Too  much  cotton  in  collodion.  Im¬ 
mersing  too  quickly.  Grreasiness  of  plate.  Too  much  alcohol 
in  proportion  to  ether. 

5.  Iodide  comes  off  in  the  Bath ,  in  Flakes.— Too  little  cotton  in 
collodion. 

6.  Developer  Repelled — fails  to  moisten,  or  to  act  upon  the  film 
or  parts  of  it.  Collodion  too  gelatinous  by  reason  of  cadmium 
salts.  Too  much  ether  for  the  alcohol.  Alcohol  and  ether  too 
strong.  Bad  cotton.  Waiting  too  long  before  immersion.  Plate 
kept  too  long  after  removing  from  negative  bath,  so  that  it  be¬ 
comes  surface-dry  in  spots. 

7.  Bluish  Deposit  in  Shadows. — Insufficient  acid  in  negative 
bath.  (This  appearance  is  not  unfrequent  in  the  glycerine  and 
honey  process.) 

8.  Ghost  or  Flare. — Indistinct  thicker  spot  on  the  plate  opposite 
centre  of  lens.  Faulty  lens  needing  to  be  rejected. 

9.  Transparent  Insensitive  Band  around  the  Plate . — Too  long 
delay  between  coating  and  immersing  the  plate. 

10.  Plates  have  a  Dusty ,  Powdery  Look. — Excessive  deposit  of 
iodide  of  silver.  Filter  after  diluting,  precisely  as  for  pinholes. 
Note,  this  is  not  to  be  confounded  with  Granularity ,  which  see, 
but  the  film  is  in  this  case  more  veiled. 

II.  Failures  belonging  especially  to  Negatives. 

1.  Too  Little  Density. — 1.  Too  weak  a  bath.  2.  Too  strong  a 
bath.  3.  Over-exposure.  4.  Too  short  a  development.  A  be- 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  335 

ginner  is  often  so  afraid  of  fogging,  that  he  cuts  short  the  develop¬ 
ment  when  the  negative  has  only  reached  the  ambrotype  stage. 

5.  Insufficient  illumination. 

2.  Excessive  Density. — 1.  Over-development,  especially  with 
under-exposure.  2.  Too  much  salting. 

3.  Solarization ,  results  from  over-exposure.  For  a  film  ex¬ 
posed  to  light  for  a  gradually  increasing  time  gains  in  strength 
up  to  a  maximum  point,  then  remains  stationary  for  an  exceed¬ 
ingly  short  time  (in  case  of  iodide  of  silver),  and  then  loses  again 
in  the  over-exposed  parts,  showing  little  tendency  to  take  a  de¬ 
posit  under  the  developer.  A  great  disposition  to  solarization 
in  a  collodion  indicates  an  insufficiency  of  bromides ;  the  ten¬ 
dency  of  bromides  is  greatly  to  prolong  the  stationary  point  just 
spoken  of. 

III.  Failures  belonging  especially  to  Ambrotypes  and 

Ferrotypes. 

1.  Want  of  Detail  in  Shadows. — Under-exposure.  Too  little 
bromide  in  collodion.  '  Too  old  and  red  a  collodion.  Insufficient 
development.  Too  acid  a  negative  bath.  Too  thin  a  collodion. 

2.  Want  of  Detail  in  High  Lights ,  which  are  at  the  same  time 
vigorous  and  dense.  Too  much  development,  so  that  the  plate 
tends  to  become  a  negative. 

3.  Grayishness  or  Want  of  Contrast. — Over-exposure:  in  this 
case  the  shadows  are  good  in  respect  of  detail,  but  want  depth. 
Use  of  hyposulphite  of  sodium  as  a  fixer  instead  of  cyanide. 

4.  Veiling  of  the  Shadows. — Over-exposure.  Too  new  a  coilo- 
dion.  Add  a  little  tincture  of  iodine,  or  mix  with  some  old  red 
collodion. 

5.  Excessive  Contrast. — Too  old  a  collodion ;  too  acid  or  foul  a 
bath.  Too  little  bromide  in  collodion.  Under-exposure. 

6.  Dark  rounded  Spots  visible  after  backing.  Pouring  on  the 
developer  like  collodion  instead  of  sweeping  it  from  along  one 
edge. 

7.  Want  of  Transparency  in  the  Film  when  Dry. — Bad  cotton. 

8.  Too  Slow  a  Development ,  may  arise  from  too  much  acidifica¬ 
tion  of  the  bath. 

9.  Green  or  Blue  Color  in  the  Film ,  according  to  Hardwich,  may 
arise  from  too  scanty  a  deposit  of  silver,  depending  upon  either 


386 


PHOTOGRAPHIC  MANIPULATIONS. 


insufficient  development  or  over-exposure,  or  from  too  thin  a 
collodion  film.  A  bad  cotton  or  a  disordered  bath  may  likewise 
affect  unfavorably  the  color  of  the  image. 

IV.  Failures  in  Paper  Development. 

Much  that  has  been  already  said  applies  itself  necessarily  to 
working  with  paper,  especially  the  remarks  on  fogging ,  and 
effects  of  under  and  over-exposure. 

Harshness.—^ Too  much  iodide. 

Stains  are  often  ascribable  to  handling  with  not  perfectly  clean 
fingers.  Indeed,  so  absorbent  is  paper,  that  almost  any  touch 
will  become  visible  to  the  developed  print,  even  with  very  clean 
fingers.  The  addition  of  bromide  has  a  great  tendency  to  check 
the  staining ;  and  in  the  case  of  positive  printing  by  development, 
where  extreme  brevity  of  exposure  is  not  important,  it  will  be 
found  best  to  develop  on  chloride  of  silver. 

The  use  of  very  weak  gallic  acid  in  connection  with  a  lead  salt 
and  acetic  acid,  as  proposed  by  the  writer,  and  explained  else¬ 
where,  exposes  less  to  danger  of  stains  than  other  modes  of 
development. 

SunJc-in  Appearance. — All  development  tends  to  this  effect ; 
developed' pictures  are  always  less  brilliant  than  sun-prints — the 
picture  does  not  so  much  lie  upon  the  surface.  Nor  is  it  easy  to 
state  the  causes  upon  which  a  more  or  less  sunk-in  effect  depends, 
though  the  quality  of  the  paper  appears  to  have  very  much  to 
do  with  it.  It  is  far  more  difficult  to  find  a  good  paper  for  de¬ 
veloping  upon,  than  for  ordinary  silver  printing.  When  the 
photographer  finds  paper  that  will  yield  a  bright  print  by  deve¬ 
lopment,  such  paper  should  be  carefully  placed  aside  for  this  use, 
and  an  exact  note  should  be  made  of  the  details  of  the  method 
which  was  found  to  give  good  results  with  it. 

V.  Silver  Printing. 

§  1. — Failures  common  to  Glass  and  Paper  Prints. 

1.  Weak  Gray  Prints. — Use  of  negatives  destitute  of  light  and 
shade,  generally  from  over-exposure  or  bad  manipulation.  Also 
may  arise  from  bad  paper  or  too  weak  or  exhausted  positive  bath. 

2.  Harsh  Black  and  White ,  or  Snoivy  Prints. — Over- developed 
negatives.  Strong  negatives,  which  would  give  good  prints  with 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  337 

sunlight,  may  produce  this  fault  in  printing  by  diffuse  light, 
especially  if  the  light  is  weak,  or  the  nitrate  bath  very  rich. 

3.  Whites  turn  Yellow. — Throwing  the  prints  into  the  toning 
bath  without  thoroughly  removing  the  nitrate  of  silver  by  wash¬ 
ing,  tends  to  yellowness  of  the  whites.  Also  exposure  of  the 
sensitive  surface  to  light.  Old  hyposulphite  causes  the  same 
fault.  Paper  kept  too  long  after  sensitizing.  Eemedy  :  Use  the 
author’s  method  of  printing  described  at  page  277. 

Some  hold  that  the  turning  yellow  depends  upon  the  bath 
solution  having  penetrated  through  the  albumen  to  the  paper 
beneath,  and  that  consequently  the  shortest  practicable  time  that 
the  paper  is  left  on  the  bath  the  better,  especially  in  hot  weather. 

It  is  found  that  paper,  after  sensitizing,  may  be  washed  off  with 
pure  water,  and  that  in  that  condition  it  keeps  many  days.  Be¬ 
fore  use,  the  sensitiveness  is  to  be  restored  by  strong  priming. 
Even  without  this  it  will  print  with  very  strong  dense  negatives. 
Hyposulphite  dust  about  the  room.  Remedy :  Tone  in  a  separate 
room. 

4.  Prints  weakening  in  the  Toning  Bath. — Use  of  bath  too  soon 
after  making.  Insufficient  printing.  Use  of  an  acid  toning  bath. 
Remedy:  Add  bicarbonate  of  sodium,  or  better,  acetate  of  sodium. 

5.  Prints  refuse  to  Tone. — Toning  bath  badly  made  or  acid 
(see  article  on  Toning  Baths).  Too  acid  or  too  weak  a  printing 
bath.  An  acid  printing  bath  often  gives  prints  that  will  not  tone 
well.  Remedy:  Drop  in  ammonia  till  the  bath  is  alkaline  to  test 
paper.  Or  fume  adulterated  chloride  of  gold,  or  exhausted  bath. 
Insufficient  washing  before  immersion  in  the  toning  bath.  Too 
cold  a  temperature ;  the  bath  generally  works  better  at  blood- 
heat.  Print  kept  too  long  after  printing.  Impurity  introduced 
into  the  toning  bath,  especially  a  trace  of  hyposulphite.  Toning 
bath  too  freshly  mixed  or  too  strong.  Fuming  for  too  long  a 
time  with  too  much  ammonia. 

6.  Prints  lose  too  much  Intensity  in  Fixing. — Insufficient  print¬ 
ing,  but  oftener  too  tbin  a  negative ;  or  may  arise  from  too  weak 
a  positive  bath.  Or  they  may  have  been  fumed  too  long. 

7.  Toned  and  Fixed  Print  too  Red, — Insufficient  toning.  Con¬ 
tinue  the  toning  till  the  redness  is  gone  when  the  print  is  held 
up  to  the  light  and  looked  through,  but  avoid  over-toning. 

8.  Fixed  and  Toned  Print  too  Blue. — Over-toning.  Poor  tones , 
or  a  want  of  richness  of  tone,  may  arise  from  conducting  the 
toning  operation  too  rapidly. 


338 


PHOTOGRAPHIC  MANIPULATIONS. 


9.  White  Spots. — Air-bubbles. 

10.  Albumen  dissolves  in  the  Sensitizing  Bath. — The  bath  is  either 
too  weak ,  or  alkaline  ;  the  remedy  is  obvious. 

11.  Over- Printing. — A  very  weak  solution  of  cyanide  of  potas¬ 
sium  is  the  best  means  of  reducing  over-printed  positives.  It 
must  be  applied  carefully,  both  as  respects  the  print  and  the 
operator,  and  the  fingers  should  not  be  immersed  in  it.  Strength 
proper  will  be  about  a  half  grain  to  ounce  of  water,  or  even  less. 

§  2. — Failures  Peculiar  to  Silver  Printing  on  Paper. 

Albumenized  Paper  repels  the  Positive  Bath. — Paper  too  dry. 
Leave  for  twenty-four  hours  in  damp  place  before  sensitizing,  or 
blot  off  the  paper  immediately  on  taking  it  from  the  printing 
bath,  between  folds  of  clean,  white  blotting-paper. 

Stains  in  the  Print  as  it  comes  from  the  Frame. — 1.  Soiled  fingers 
handling  the  paper.  Too  much  care  can  never  be  taken  in  hand¬ 
ling  photographic  paper.  The  sources  of  stains  by  soiled  or 
moist  fingers  undoubtedly  often  precede  the  purchase;  in  this  the 
professional  photographer  has  a  great  advantage  over  the  ama¬ 
teur,  that  his  paper  is  purchased  in  quantities,  and  so  undergoes 
far  less  fingering.  Two  corners  of  the  sheet,  whether  whole  or 
cut  up,  should  at  once  be  folded  down  at  the  commencement  of 
operations,  and  no  other  part  of  the  paper  be  touched  from  first 
to  last. 

Care  will  not  only  be  required  as  to  the  handling,  but  as  to 
everything  that  the  paper  comes  into  contact  with. 

2.  A  very  common  source  of  stains  is  the  presence  of  very  fine 
metallic  particles  in  the  paper,  produced  by  the  grating  of  the 
mill-machinery.  These  particles,  however  infinitesimal,  become 
causes  of  reduction,  and  inevitably  make  stains. 

3.  Imperfect  removal  of  hyposulphite  used  in  bleaching. 

4.  Foreign  substances  of  almost  any  sort,  constituting  invisible 
imperfections  in  the  paper.  These  may  act  in  several  ways.  They 
may  diminish  the  penetrability  of  the  paper  locally.  Such  por¬ 
tions  will  take  up  less  silver  and  print  lighter  than  the  rest. 
Often  these  foreign  matters  can  be  detected  by  holding  the  paper 
up  to  the  light  and  observing  its  regularity. 

5.  Irregular-  distribution  of  resin  or  other  sizing  material 
through  the  paper.  Resin  easily  combines  with  silver,  making  a 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  339 

sensitive  compound.  If  the  resin  is  not  equally  distributed,  the 
quantity  of  silver  compound  will  vary  accordingly. 

6.  Reflected  light  from  bright  objects  near  the  printing  frame. 

7.  Printing  by  sunlight  through  a  window-frame,  with  irregu¬ 
larities  in  the  glass. 

8.  Paper  not  well  floated  on  the  bath,  or  left  on  it  an  insuffi¬ 
cient  time  for  the  equal  absorption  of  nitrate,  causing  irregular 
marbled  stains. 

9.  Impurities  floating  on  the  surface  of  the  printing  bath,  taken 
up  by  the  paper. 

Irregular  or  patchy  effects  in  printing  may  be  caused  by  fuming 
for  too  short  a  time. 

Spots  appearing  in  the  Toning. — Neglect  to  keep  the  prints 
moving.  Where  one  print  rests  upon  another,  the  action  of  the 
toning  bath  is  slower,  and  a  spot  results.  This  is  a  very  common 
source  of  trouble,  unless  the  necessity  of  care  is  borne  steadily  in 
view ;  or  if  the  print  floats  on  the  bath,  instead  of  being  kept 
under  the  surface. 

Spots  in  the  Fixing. — Adhesion  of  prints  to  each  other  in  the 
bath,  by  neglect  to  continually  move  them. 

Want  of  Brilliancy. — Floating  the  paper  too  long  on  printing 
bath.  Half  a  minute  to  three-quarters  is  sufficient,  and  gives  a 
far  better  print  than  a  longer  time. 

Prints  have  a  Sunk-in  or  Mealy  Appearance. — Insufficient  albu- 
menizing.  Bad  paper.  Old  and  foul,  or  acid,  printing  bath. 
Too  much  salting.  Old  albumenized  paper  that  has  not  been 
kept  thoroughly  dry,  especially  if  chloride  of  sodium  has  been 
used  for  salting.  Dampness  causes  the  chloride,  which  should 
be  wholly  in  the  layer  of  albumen,  to  penetrate  into  the  body  ot 
the  paper.  Printing  bath  too  newly  made,  or  paper  floated  too 
long.  Too  much  fuming  with  ammonia,  or  too  strong  fuming, 
tends  to  produce  a  flat,  mealy  print. 

Print  refuses  to  Bronze  in  the  Shadows  while  Printing. — This  de¬ 
pends  upon  the  salting  bath  having  been  too  strong  for  the  print¬ 
ing  bath.  Remedy :  Add  more  nitrate  of  silver  to  the  positive 
bath,  or  change  the  paper.  Paper  kept  too  long  after  sensitizing. 

If  the  image  does  not  bronze  in  the  shadows  by  the  aid  of  the 
printing,  a  brilliant  print  cannot  be  expected.  An  opposite  cause 
may  be  expected  to  produce  the  opposite  effect,  viz.,  too  deep 
bronzing  and  too  harsh  a  print. 

Print  takes  a  different  tone  at  the  two  ends,  as,  one  end  black 


340 


PHOTOGRAPHIC  MANIPULATIONS. 


and  the  other  blue,  or  one  black  and  the  other  brown.  Cause, 
irregular  albumenizing  of  the  paper,  so  that  the  coat  of  albumen 
is  thicker  at  one  part  than  another;  where  the  albumen  is  thinnest 
the  toning  proceeds  most  rapidly.  For  this  reason  it  is  especially 
important,  for  large  prints,  to  select  the  paper  carefully. 

Black  Dot  with  a  White  Tail. — If  the  pin  to  which  the  sheet 
hung  to  dry  was  put  through  a  wet  place,  a  local  reduction  fol¬ 
lows  with  this  result.  Pins  left  for  some  hours  in  an  old  cyanide 
fixing  bath  become  silvered,  and  are  exempt  from  this  trouble ; 
silver  may  be  dissolved  in  cyanide  for  the  purpose. 

Albumen  dissolves  off  in  the  Silvering  Bath. — Bath  is  either  too 
alkaline  or  too  weak  in  silver. 

Failures  appearing  only  in  the  Toned  and  Fixed  Print. — Troubled 
appearances  in  the  substance  of  the  paper.  1.  If  the  chloride  of 
silver  has  not  been  thoroughly,  or  rather  has  been  very  imper¬ 
fectly  removed,  the  print  has  a  mottled  look  on  holding  up  to  the 
light,  and  as  this  remaining  chloride  of  course  darkens  by  con¬ 
tinued  exposure  to  light,  the  mottled  appearance  becomes  with 
time  more  perceptible.  This  imperfect  removal  may  arise  from 
not  leaving  long  enough  in  the  hyposulphite  bath,  or  from  the 
exhaustion  of  the  bath,  or,  possibly,  by  exposure  to  light  before 
fixing.  The  first  are  the  most  probable  causes.  Remedy  :  Use 
hyposulphite  of  sodium  liberally ;  one  pound  to  twelve  sheets  is 
none  too  much.  Make  no  more  than  wanted,  and  begin  each 
day  afresh,  under  no  circumstances  using  a  bath  a  second  day, 
even  if  but  a  single  print  was  fixed  in  it  the  previous  day. 

2.  Cases  have  been  observed  in  which  the  prints  were  in  per¬ 
fect  order  when  toned  and  fixed,  and  yet  exhibited  stains  after 
the  final  washing.  This  has  been  found  to  arise  from  the  use  of 
zinc  vessels,  or  a  zinc  bottom  to  the  washing  trough.  The  more 
thoroughly  the  vessel  is  cleaned,  the  worse  the  spots.  Remedy  : 
Varnish  thoroughly  the  whole  surface  of  the  zinc,  or  have  a 
wood  bottom  with  a  layer  of  white  quartz  pebbles  (which  may 
be  obtained  from  those  who  make  a  business  of  gravel-roofing). 
These  are  easily  kept  clean. 

Over-contrast. — If  necessary  to  print  from  a  negative  too  harsh, 
the  excess  of  contrast  can  be  reduced  by  exposing  the  paper  to 
light  for  a  few  seconds,  or  a  minute,  before  placing  it  in  the 
printing  frame.  The  print  is  thus  somewhat  improved,  but  will 
never  be  first-rate. 

Hard  negatives  will  require  light  silvering.  It  often  happens 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  341 


that  a  negative  is  full  of  detail,  and  unobjectionable  in  every  re¬ 
spect  except  that  of  being  so  dense  that  the  shadows  of  the  print 
are  overdone  before  the  detail  in  the  lights  come  out.  Such 
negatives  will  need  paper  very  lightly  silvered.  Often  the  paper 
after  going  through  the  regular  sensitizing  may  be  floated  for  a 
minute  on  water.  The  writer  has  seen  most  beautiful  results  got 
in  this  way  from  negatives  that  would  not  give  any  good  effect 
with  ordinary  silvered  paper. 

Blurred  Spots. — A  bad  frame  may  not  have  brought  the  paper 
home  to  the  glass  everywhere.  Many  printing  frames  are  very 
defective  in  this,  that  they  throw  all  the  strain  into  the  middle  of 
the  plate,  thereby  endangering  the  safety  of  the  negative,  and  get¬ 
ting  bad  definition  at  the  edges,  which  is  apt  to  be  attributed  to  a 
falling  off  in  the  power  of  the  lens.  Try  the  frames  always  with 
a  piece  of  plain  glass,  fastening  down  the  springs  and  pressing  up 
the  glass  with  the  thumbs  on  various  parts  in  succession,  to  find 
how  the  pressure  produced  by  the  springs  is  distributed.  The 
old  pattern,  with  bars  at  the  back,  is  the  best  by  far. 

Blistering  of  the  Albumen. — 1.  Peculiarity  of  the  albumen  film 
which  will  not  bear  the  sudden  change  from  the  fixing  bath  to 
pure  water  without  endosmose.  Remedy  :  Let  the  prints  lie  for 
a  short  time  in  a  weak  intermediate  bath  of  hyposulphite,  between 
the  regular  fixing  bath  and  the  washing.  2.  Acid  washing  after 
toning  in  an  alkaline  gold  bath  containing  alkaline  carbonates. 
3.  Over-dryness  of  the  albumenized  paper.  For  this  and  other 
reasons  it  is  a  good  plan  to  leave  the  paper  for  a  day  before  using 
it  in  a  damp  place;  not  too  damp,  however,  nor  for  too  long  a 
time,  as  this  would  lead  to  the  working  inwards  of  the  salting, 
occasioning  a  loss  of  brilliancy  to  the  print. 

It  has  been  said  that  the  addition  of  a  small  quantity  of  ether 
(J  ounce  to  20 -ounce  bath)  to  the  fixing  bath  will  prevent  blister¬ 
ing. 

Fading  of  the  Prints. — Insufficient  washing.  Old  hyposulphite 
fixing  baths.  A  solution  of  hyposulphite  of  sodium  in  water 
keeps  perfectly.  But  if  used,  it  should  be  rejected  and  not  em¬ 
ployed  on  any  subsequent  day  to  that  on  which  it  was  first  used. 
Acid  in  the  fixing  bath.  Use  of  a  fixing  and  toning  bath. 

Black  Specks  showing  first  after  Mounting. — Appearances  of  this 
sort  may  almost  invariably  be  traced  to  the  agency  of  fine  metal¬ 
lic  particles.  These,  by  the  aid  of  atmospheric  moisture,  gradu¬ 
ally  act  upon  the  print  and  produce  the  specks.  They  come — 


342 


PHOTOGRAPHIC  MANIPULATIONS. 


1.  By  trimming  the  print  upon  a  brass  plate.  The  point  of  the 
knife  detaches  fine  particles  of  metal,  these  are  by  the  pressure 
forced  into  the  print  and  soon  make  stains  upon  it.  Glass  or  hard 
wood  should  be  used  to  cut  on. 

2.  By  using  a  brass  form  to  trim  by.  Particles  are  abraded 
and  enter  the  print  in  the  same  way  as  before.  Steel  or  glass 
forms  should  be  used  exclusively. 

3.  By  using  Bristol  board  for  mounting,  on  which  borders  or 
designs  have  been  printed  in  gold  or  bronze.  The  designs  are 
printed  in  varnish  and  the  metallic  powders  are  rubbed  on; 
grains  adhere  elsewhere  than  on  the  design,  and  are  not  entirely 
removed  in  the  subsequent  brushing,  but  eventually  destroy  the 
print. 

Crystallizations  in  the  printing  bath  or  on  the  paper  may  occur 
in  consequence  of  the  nitric  acid  used  in  preparing  the  ammonio- 
nitrate  bath  containing  sulphuric  acid :  sulphate  of  silver  is  but 
very  slightly  soluble  in  water.  A  bath  so  contaminated  may  be 
brought  into  order  by  adding  nitrate  of  baryta  in  solution  so  long 
as  a  precipitate  forms.  The  same  substance  may  be  used  to  test 
the  purity  of  the  nitric  acid  used,  and  also  to  purify  it,  if  found 
contaminated.  When  nitrate  of  baryta  is  added  to  a  liquid  con¬ 
taining  sulphuric  acid,  sulphate  of  baryta ,  a  very  insoluble  salt,  is 
thrown  down  as  a  heavy  white  powder,  easily  separated  either 
by  decantation  or  filtration. 

Cracks  or  Ruptures  in  the  Albumen  Coat  are  sometimes  produced 
by  drying  the  print  too  rapidly.  Dry  slowly  at  ordinary  tem¬ 
peratures. 


§  3.— Collodio-Chloride. 

Fading  is  said  to  be  owing  to  the  use  of  albumen  as  an  under¬ 
stratum. 

Bad  Tones. — Citric  acid  in  collodion.  Substitute  tartaric. 

Slow  Toning. — Kepellent  collodion.  Moisten  the  plate  before 
immersing  in  the  toning  solution  with  equal  parts  of  alcohol  and 
water. 

Flat ,  weak  Pictures.  —  Insufficient  quantity  of  pyroxyline  in 
collodion.  Omitting  to  fume  when  fuming  is  needed. 

Sunk-in  Prints. — The  cotton  may  not  be  suitable. 

Splitting  of  Film. — Neglect  to  edge  the  plate. 

Spots. — According  to  Mr.  Simpson,  the  discoverer  of  the  pro* 


FAILURES  IN  PHOTOGRAPHIC  OPERATIONS.  343 


cess,  spots  are  caused  by — 1.  Too  much  free  nitrate  of  silver  in 
the  collodio-chloride.  2.  Keeping  the  plates  too  long  after  coat¬ 
ing.  Dry  before  a  fire  and  expose  at  once. 

Crystallizations  in  the  Film. — Excess  of  nitrate  of  silver  in  the 
collodion.  Add  more  salting. 

Insensitiveness. — Insufficient  quantity  of  nitrate  of  silver,  more 
will  be  needed. 

Detaching  of  the  Film  (from  paper  in  the  collodio-chloride  paper 
process),  want  of  sufficient  sizing  in  the  paper.  Few  or  no  papers 
have  the  necessary  quantity,  and  a  coat  of  gelatine  is  usually 
necessary. 

Rolling  up  of  the  Prints. — This  is  an  annoying  peculiarity  of 
the  process,  and  difficult  to  avoid.  It  is  said  that  plunging  for  an 
instant  into  very  hot  water  will  destroy  the  tendency. 

Blue  Tones. — The  toning  is  much  more  rapid  than  with  albu- 
menized  paper,  and  unless  care  is  taken,  the  print  may  be  over¬ 
toned  before  the  operator  is  aware. 

Final  Observation. — In  closing  this  chapter  on  Failures,  which 
the  writer  has  endeavored  to  make  as  complete  as  possible,  he 
feels  compelled  to  remark  that  whilst  the  sources  of  non-success 
are  almost  innumerable,  none  do  anything  like  so  frequent  and 
fatal  damage  as  want  of  care  and  of  perfect  cleanliness .  The 
commonest  sources  of  trouble  are — 

1.  Use  of  insufficiently  cleaned  vessels. 

2.  Immersing  of  fingers  into  solutions,  which  fingers  have  been 
in  other  solutions  without  intermediate  washing. 

3.  Tables  slopped  with  solutions,  which  thus  adhere  to  the  bot¬ 
toms  of  bottles,  measuring  glasses,  beakers,  &c.,  so  that  when 
these  are  poured  from,  a  fatal  drop  runs  along  the  outside  from 
the  bottom  and  mixes  with  the  other  materials.  A  drop  of  hypo¬ 
sulphite  solution  will  spoil  almost  any  other  chemical  solution 
with  which  the  photographer  works.  All  these  sources  of  trouble 
have  this  in  common,  that  they  introduce  foreign  matter  into  the 
photographer’s  materials  unknown  to  him,  and  this  is  the  most 
frequent  of  all  causes  of  failure. 


344 


PHOTOGRAPHIC  MANIPULATIONS. 


CHAPTER  XY. 

OUT-DOOR  PHOTOGRAPHY  WITH  WET  AND  PRESERVED 

PLATES. 

§  1.— Wet  Plates. 

In  Chapter  VII.  most  of  the  information  necessary  for  view- 
taking  has  been  given,  nevertheless  some  special  details  remain 
to  be  noted. 

"When  negatives  are  to  be  taken  at  a  distance  from  the  dark 
room,  we  are  obliged  either  to  work  with  a  tent,  to  use  “  pre¬ 
served  plates,”  or  to  resort  to  “  dry  plates,”  which  last  method 
will  be  considered  in  subsequent  chapters. 

Although  plates  are  apt  to  deteriorate  pretty  rapidly  by  keep¬ 
ing  after  sensitizing,  yet,  with  care  and  attention,  remarkable 
delays  may  be  supported,  especially  in  cold  weather.  Heat 
hastens  the  destruction  of  the  plate.  Since  the  first  edition  of 
this  Manual  went  to  press,  the  writer  has  paid  particular  atten¬ 
tion  to  this  subject,  and  has  succeeded  in  keeping  wet  plates  in  a 
very  satisfactory  way.  His  method  will  be  found  below. 

The  following  are  the  troubles  which  will  be  apt  to  show  them¬ 
selves  : — 

1.  Fog. 

2.  Marbled  stains.  (See  also  p.  327.) 

3.  Transparent  or  hazy  spots  of  various  sizes  up  to  one-quarter 
of  an  inch  diameter,  generally  nearly  round. 

Fogging  is  not  a  very  common  trouble,  and  seems  to  depend  on 
newness  of  collodion,  for  which  a  riper  must  be  substituted. 

Marbled  stains  are  very  apt  to  come,  especially  in  hot  weather. 
After  a  careful  study  of  these  sources  of  trouble,  the  writer  ad¬ 
vises  as  follows : — 

1.  Use  a  rather  ripe  collodion  containing  a  liberal  proportion 
of  bromides  (from  2  J  to  3  grains  of  bromide  to  4  of  iodide),  and 
immerse  the  plate  into  the  sensitizing  bath  as  soon  after  coating 
as  possible.  In  hot  weather  just  as  soon  as  the  drops  cease  to 
fall. 

2.  Adopt  the  excellent  system  of  having  two  negative  baths, 


OUT-DOOR  PHOTOGRAPHY  WITH  WET  PLATES.  345 

one  to  make  the  film,  35  or  40  grains  to  the  ounce,  and  the  other 
20  to  25  grains  to  the  ouuce,  exclusively  reserved  to  pass  the 
plates  into  after  the  film  is  completely  made  to  the  first.  Thus 
the  plate  is  always  covered  with  a  comparatively  fresh,  pure 
hath  solution.  This  is  an  excellent  plan  for  general  adoption ; 
but  when  the  plates  are  to  be  kept  long,  it  is  indispensable. 

3.  Withdraw  the  plate  as  soon  as  the  oily  marks  are  gone. 

4.  Apply  thick  wet  blotting-paper  on  the  back.  This  must 
not  be  too  wet,  or  it  will  make  stains  by  running  down  the  back 
of  the  plate  and  getting  round  the  bottom  and  irregularly  diluting 
the  liquid  on  the  film. 

5.  But  the  most  important  precaution  of  all  lies  in  avoiding 
accumulation  of  bath  solution.  For  this  purpose,  the  writer, 
after  draining  the  plate  thoroughly  on  successive  pieces  of  folded 
blotting-paper,  and  wiping  the  back  thoroughly,  sets  it  in  the 
frame,  of  which  the  corners  have  been  carefully  and  thoroughly 
wiped  out  immediately  before.  A  piece  of  the  thickest  blotting 
pad  has  been  provided,  about  an  inch  wide  and  as  long  as  the 
plate.  On  the  long  side  of  this  a  narrow  edge,  about  an  eighth 
of  an  inch  wide,  is  folded  over  at  right  angles.  This  strip  is  laid 
along  the  bottom  of  the  plate,  but  the  chief  peculiarity  of  the 
arrangement  is  that  the  plate  is  lifted  up  to  the  narrow  edge  passed 
under  it.  This  edge  is  not  to  pass  between  the  face  of  the  plate 
and  the  glass  corners,  but  under  the  bottom  edge  of  the  plate.  It 
thus  comes  just  into  contact  with  the  bottom  edge  of  the  collodion 
film,  which  it  keeps  steadily  drained  during  the  whole  delay. 
This  has  a  really  wonderful  influence  in  preventing  marbled  stains , 
for  which  it  is  a  perfect  cure. 

By  operating  in  this  way,  the  writer  has  been  able  to  keep 
plates  with  facility  and  certainty  for  an  hour,  and  even  much 
longer.  On  one  occasion  a  plate  was  carried  twelve  miles,  and 
developed  at  the  end  of  nearly  two  hours  (1  hour  55  minutes), 
and  gave  an  excellent  negative.  No  preservative  was  applied, 
and  the  success  depended  upon  the  foregoing  precautions,  of 
which  a  second  bath  of  weaker  and  purer  solution,  and  the  blot¬ 
ting  pad  under  the  edge,  were  the  most  effective.  Plates  kept  for 
two  and  a  half  hours  gave  hazy  spots,  but  were  free  from  all  other 
faults.  This  mode  of  operating  the  writer  strongly  recommends. 

The  hazy  spots  are  very  annoying  and  troublesome  when  the 
delay  is  very  long ;  difficult  by  their  size  to  touch  out,  and  ruin¬ 
ing  the  picture  if  left  in.  They  appear  to  arise  from  a  concentra- 
23 


346 


PHOTOGRAPHIC  MANIPULATIONS. 


tion  of  the  bath  solution  reacting^upon  the  iodide  of  silver  in  the 
film.  The  presence  of  acid,  especially  of  nitric  acid ,  has  seemed 
to  the  writer  to  increase  this  tendency.  For  plates  that  are  to  be 
kept,  acetic  acid  is  better  than  nitric.  The  addition  of  a  few 
grains  of  acetate  of  potash  or  soda,  with  a  little  acetic  acid,  will 
change  a  bath  from  a  nitric  to  an  acetic  bath.  The  proportion  is 
roughly  about  a  grain  to  five  or  six  ounces  of  bath.  Dissolve  in 
half  an  ounce  of  water  and  pour  slowly  into  the  bath,  stirring. 
The  cloud  of  acetate  of  silver  at  first  formed  will  speedily  dis¬ 
appear. 

Tripods. — See  Chap.  VII.,  sec.  3. 

Tents  and  Boxes. — When  the  distance  of  the  object  makes  it 
clearly  impossible  to  carry  a  wet  plate,  we  must  either  use  a  dry 
one,  or  else  take  the  means  with  us  for  preparing  wet  plates  on 
the  spot. 

In  using  a  tent,  the  operator  works  inside.  With  a  developing 
box ,  he  passes  his  arms  through  sleeves  provided  with  India-rubber 
rings,  and  watches  his  operations  through  yellow  glass  let  into 
the  front  of  the  box.  Of  the  two  methods  the  former  is  the  more 
satisfactory.  With  the  box  there  is  more  danger  of  spilling  hypo¬ 
sulphite,  and  so  exposing  the  delicate  operations  of  photography 
to  the  effects  of  hyposulphite  dust. 

Of  tents,  probably  Carbutt’s  is  as  convenient  as  any.  A  still 
more  convenient  mode  of  operating  is  with  a  van ,  either  altered 
or  built  for  the  purpose.  Mr.  G.  W.  Wilson,  the  well-known 
Scotch  photographer,  recommends  a  very  light  tripod  covered 
with  two  thicknesses  of  black  calico  and  an  inner  one  of  yellow. 
The  calico  is  a  foot  longer  than  the  tripod,  on  which  extra  foot- 
stones  are  placed  to  steady  the  tent  and  exclude  light.  There  is 
probably  nothing  better  than  this  simple  and  convenient  plan. 
The  tripod  may  be  very  light,  and  of  course  folds  up  into  a  small 
space,  so  that  the  whole  weight,  including  that  of  the  cover,  is 
trifling.  An  umbrella  has  been  found  an  excellent  support  for  a 
tent ;  it  is  secured  to  a  stake  driven  in  the  ground,  and  an  opaque 
cloth  thrown  over  it ;  a  piece  of  yellow  muslin  set  in,  lets  in  light 
enough  to  work  by,  and  water  is  introduced  from  a  vessel  outside 
by  a  flexible  tube.  An  exceedingly  convenient  arrangement  has 
been  made  by  altering  an  old  barouche,  the  front  part  being 
arranged  with  an  operating  table  and  racks  for  bottles,  the  photo¬ 
grapher  sitting  on  the  back  seat  to  sensitize  and  develop. 

Where  the  object  is  rather  lightness  than  folding  up  into  short 


OUT-BOOR  PHOTOGRAPHY  WITH  WET  PLATES.  347 

lengths,  three  pieces,  or  four  if  preferred,  of  cane-angle  may  he 
fastened  together  at  one  end  and  a  cloth  thrown  over  them. 

Any  of  these  plans  seem  preferable  to  the  more  elaborate  sort, 
which  are  heavier  to  carry,  and  require  the  loss  of  valuable  time 
to  put  them  together  and  get  the  whole  concern  into  working 
order.  It  is  to  be  remarked,  both  with  this  plan  and  that  of  the 
tripod,  that  the  wider  the  stride  given  to  the  legs  the  steadier  the 
whole  arrangement. 

Shortening  the  Out-door  Worh. — Various  plans  have  been  found 
useful  to  cut  short  the  development  and  postpone  the  fixing  (also 
a  redevelopment,  if  needed)  until  it  can  be  conveniently  finished 
in  the  dark  room  at  home. 

The  first  plan  used  was  to  flow  the  plate  with  glycerine  to 
which  a  little  water  had  been  added,  but  this  has  given  way  to 
the  syrup  treatment.  A  filtered  mixture  of  clear  syrup  molasses 
and  water  is  provided,  and  as  soon  as  the  development  is  over, 
the  plate  is  carefully  flowed  with  it,  and  in  this  condition  may  be 
kept  for  a  day  or  two.  Mr.  Gulliver  makes  a  decoction  of  saffron 
in  water,  to  be  used  in  the  same  way,  and  lines  the  top  and  bot¬ 
tom  of  the  plate  box  with  wet  felt.  Some,  in  using  syrup,  add 
alcohol,  as  follows : — 

Syrup  molasses . 10  ounces. 

Water . 10  “ 

Alcohol . 6  drachms. 

The  plate  is  then  slid  into  a  groove  in  a  light  tight  box  of 
wood  or  tin.  It  must  be  well  washed  before  redeveloping. 

g  2. — Instantaneous  Photography. 

When  objects  in  motion  are  to  be  photographed,  it  becomes 
necessary  that  the  exposure  should  be  so  reduced  that  the  move¬ 
ment  shall  be  inappreciable.  To  these  exposures  the  name  of 
“instantaneous”  has  been  applied,  although  they  are  in  many 
cases  reduced  to  a  small  fraction  of  a  second.  Various  contriv¬ 
ances  have  been  devised  for  effecting  them.  The  most  usual  and 
one  of  the  best  is  to  have  a  slide  attached  to  the  camera  front, 
capable  of  moving  up  and  down  in  a  groove.  In  its  centre  is  a 
circular  opening  of  an  inch  or  two  in  diameter.  When  the  slide 
is  up  or  down  it  covers  the  lens,  but  in  descending  it  uncovers  it 
for  the  space  of  time  that  the  circular  opening  takes  to  pass  the 
front  of  the  lens. 


348 


PHOTOGRAPHIC  MANIPULATIONS. 


For  exposures  which,  though  brief,  are  to  be  longer  than  those 
attained  as  above  described,  the  cap  may  be  removed  and  instantly 
replaced.  This  is  best  done  by  raising  the  lower  part  whilst  the 
upper  part  is  held  nearly  still,  almost  like  turning  upon  a  hinge. 
In  this  way  the  foreground  gets  a  much  longer  exposure  than 
the  distance  and  sky.  Another  method  is  to  let  the  focussing 
cloth  hang  over  the  uncapped  lens  ;  the  palm  of  the  hand  is  placed 
over  the  lens,  and  the  corner  of  the  cloth  held  between  the  thumb 
and  the  lower  part  of  the  forefinger.  The  hand  being  then  turned 
upwards  over  its  own  back  edge  as  an  axis,  uncovers  the  lens 
for  a  moment  and  is  instantly  returned,  in  both  cases  carrying 
the  cloth  with  it.  As  in  the  former  case,  this  exposes  the  fore¬ 
ground  longer  than  the  sky. 

The  conditions  under  which  instantaneous  pictures  are  to  be 
taken  differ  extremely.  Widely  extended  views  throw  back  a 
great  volume  of  light  and  much  facilitate  the  operation.  Ships 
at  sea,  with  breaking  waves,  offer  no  very  serious  difficulty,  if 
the  size  of  the  plate  is  not  too  large.  River  scenes,  with  sail 
boats  and  steamboats,  are  similar  in  character.  Instantaneous 
views  of  these  subjects  will  be  best  taken  with  the  Steinheil 
aplanatic  or  the  Dallmeyer  rapid  rectilinear,  remembering  always 
that  the  shorter  the  focal  length  the  more  powerful  the  image, 
and  that  success  is  thereby  very  greatly  facilitated. 

On  the  other  hand,  objects  in  motion  near  by,  sending  back 
comparatively  little  light,  no  matter  how  brightly  they  are  illu¬ 
minated,  will  be  most  easily  managed  with  a  portrait  lens.  But 
as  this  lens  has  comparatively  little  depth  of  focus,  care  must  be 
taken  to  get  the  objects  pretty  nearly  into  the  same  plane;  and 
as  the  corners  will  be  very  apt  to  be  out  of  focus,  it  may  be 
necessary  to  vignette  the  negative  in  printing. 

The  Chemicals . — The  bath  should  be  forty  grains  to  the  ounce, 
new  or  nearly  new,  and  nearly  neutral.  The  collodion  should  be 
just  old  enough  to  work,  and,  what  is  of  special  importance,  must 
be  made  of  cotton  of  a  very  sensitive  character.  Cotton  capable 
of  giving  intense  images  that  need  no  redevelopment,  does  not 
possess  the  exalted  sensibility  necessary  for  instantaneous  work ; 
we  need  a  cotton  of  a  very  impressible  character,  and  this  is 
usually  accompanied  by  a  tendency  to  form  images  needing  re¬ 
development.  Without  a  suitable  cotton,  it  will  be  hopeless  to 
attempt  the  work.  The  developer  must  contain  no  restraining 
acid,  and  be  simply  an  eighty-grain  solution  of  sulphate  of  iron. 


OUT-DOOR  PHOTOGRAPHY  WITH  WET  PLATES.  349 

The  development  must  be  very  brief,  or  such  a  developer  will 
produce  fog. 

The  subject  must  not  present  difficulties  too  great.  The  illu¬ 
mination  must  be  good  everywhere,  and  there  must  be  no  strong 
contrasts.  Objects  in  motion  will  be  much  more  easily  taken 
when  their  line  of  movement  is  either  towards  or  from  the  ope¬ 
rator.  An  object  passing  rapidly,  directly  in  front  of  the  camera, 
will  be  exceedingly  difficult  to  catch  successfully ;  it  is,  however, 
accomplished. 

Instantaneous  views  are  most  easily  obtained  in  the  spring,  at 
which  season  the  light  is  more  active  than  at  any  other.  There¬ 
fore  those  who  especially  interest  themselves  in  this  branch  of 
work  find  it  desirable  to  accomplish  it  in  May  and  June. 

It  is  a  not  uncommon  mistake  for  those  who  desire  to  have  a 
“  quick  acting  collodion,”  to  seek  for  it  in  some  special  formula. 
This  is  all  a  delusion.  A  highly  sensitive  collodion  is  one  made 
with  a  highly  sensitive  cotton.  As  for  the  formula  of  salting,  a  few 
trials  of  different  proportions  of  bromide  must  determine  what  is 
best  suited  to  it.  But  what  suits  one  specimen  may  not  suit 
another.  One  way  is  to  make  with  the  cotton  a  collodion  con¬ 
taining  but  little  bromide  (as,  for  example,  by  Beutlinger’s 
formula,  p.  142).  If  on  trial  it  seems  sensitive,  make  up  another 
portion  by  a  formula  rich  in  bromide,  and  compare  these,  and 
one  or  two  mixtures  of  each,  in  different  proportions. 

Mr.  Chapman  recommends  after  the  iron  development  has  done 
all  that  it  can,  to  wash  it  off  and  to  apply  an  alkaline  develop¬ 
ment  with  pyrogallic  acid  (see  Chap.  XVI.);  when  this  ceases  to 
act,  to  finish  with  acid  pyro  and  silver  in  the  ordinary  way. 

The  writer  has  found  that  a  very  material  acceleration  can  be 
obtained  by  lining  the  inside  of  the  camera  with  pasteboard 
which  has  been  colored  red  with  carmine  dissolved  in  water  with 
the  aid  of  a  drop  or  two  of  ammonia.  This  pasteboard  is  not 
to  line  the  whole  of  the  inside  (see  Fig.  107,  p.  220),  but  only 
those  parts  where  the  light  is  least  strong — opposite  ground  and 
trees,  but  not  sky. 

The  red  rays  of  light  have  a  continuing ,  but  no  exciting  power. 
They,  therefore,  exalt  the  action  of  the  image  upon  the  plate, 
and,  when  rapidity  is  an  object,  this  method  will  be  found  de¬ 
cidedly  advantageous. 

Animals. — Very  beautiful  photographs  are  obtained  of  horses, 
dogs,  cattle,  &c.  In  order  not  to  risk  motion  of  the  subject,  it  is 


350 


PHOTOGRAPHIC  MANIPULATIONS. 


best  to  make  very  brief  exposures,  simply  uncapping  and  in¬ 
stantly  replacing  the  lens.  A  quarter-size  portrait  lens  is  the 
most  suitable.  If  larger  pictures  are  desired,  it  is  best  to  take 
tbe  small  size  just  mentioned  and  to  enlarge  afterwards.  This  is 
the  method  adopted  by  Mr.  Schreiber,  of  this  city,  who  makes 
this  subject  a  specialty,  and  who  has  shown  the  author  of  this 
manual  some  very  fine  enlargements,  taken  from  quarter-plate 
negatives.  He  prefers  to  take  even  small  animals,  such  as  dogs, 
in  the  open  air,  with  appropriate  surroundings,  rather  than  under 
the  skylight. 


\  3. — Preserved  Plates — The  Glycerine  Process. 

The  preserved  plate  stands  intermediate  between  the  wet  and 
the  dry.  Of  various  preservative  processes,  the  glycerine  and 
honey,  first  brought  prominently  forward  by  Mr.  W.  H.  Harrison, 
is  the  best.  A  plate  coated  and  sensitized  as  usual  is  plunged 
without  previous  washing  into  a  bath  prepared  as  follows  : — 


Price’s  glycerine . 2  ounces. 

Pure  honey  2  “ 

Ordinary  bath  solution . 2  “ 

Water . 2  “ 

Glacial  acetic  acid . 8  drops. 


These  are  well  shaken  up  and  set  in  the  sun  for  a  few  hours, 
or  still  better,  a  day,  then  half  an  ounce  of  kaolin  is  added,  well 
shaken  up,  and  the  whole,  after  standing  for  a  day,  is  filtered  into 
a  bottle.  A  large  funnel  with  a  filter  in  it  is  left  permanently  in 
the  neck  of  the  bottle.  When  wanted  for  use,  a  sufficient  quan¬ 
tity  is  to  be  poured  into  a  pan.  After  using  it,  it  is  poured  back 
into  the  funnel ;  it  is  a  saving  of  trouble  to  have  the  funnel  large 
enough  to  carry  the  whole  at  once ;  the  mixture  is  then  always 
through  and  ready  for  next  day.  The  glycerine  keeps  the  filter 
moist  and  ready  to  filter  well  and  rapidly. 

The  sensitive  bath  is  a  common  acetic  bath,  a  bath  acidulated 
with  nitric  acid  does  not  work  well.  The  usual  formula  for  the 
glycerine  preservative  does  not  include  the  acetic  acid  as  above, 
but  the  writer  has  found  a  marked  advantage  from  adding  it. 

As  above  directed,  the  preservative  bath  contains  about  eight 
grains  of  nitrate  of  silver  to  the  ounce.  By  use  it  becomes  con¬ 
tinually  richer  in  silver,  and  thereby  deteriorated — from  eight  to 
ten  grains  is  its  proper  dose.  Therefore  we  must  add  glycerine 


DRY  PLATE  PHOTOGRAPHY. 


351 


and  honey,  and  if  necessary  a  little  water  from  time  to  time  to 
maintain  a  correct  proportion.  After  such  addition  it  must  inva¬ 
riably  be  sunned  and  shaken  up  with  kaolin  again. 

The  devebpment  of  these  plates  takes  place  in  the  ordinary  way 
with  an  iron  developer  or  with  a  pyrogallic  one.  In  the  former 
case,  an  exposure  about  three  times  as  long  as  for  wet  collodion 
is  proper.  With  a  pyrogallic  development  a  longer  exposure  is 
needed;  this  mode  is  preferred  by  Mr.  Harrison,  as  allowing  of 
more  latitude  in  exposure.  The  writer’s  trials  have  worked  best 
with  iron  development;  for  this  purpose  he  does  not  like  the 
plain  iron  developer  so  much  as  the  sugar  developer.  (Seep.  164.) 
The  development  is  generally  best  done  in  a  pan.  The  edges 
sometimes  become  a  little  dry,  especially  if  the  plate  has  been 
kept  six  to  twelve  hours ;  and  then  these  do  not  take  the  de¬ 
veloper  evenly,  and  the  edges  may  be  defective  even  when  all 
the  rest  of  the  plate  is  good,  unless  developed  in  a  pan.  A  red 
transparent  sky  indicates  over-exposure. 

This  method  will,  when  well  managed,  give  results  about  as 
good  as  ordinary  wet  work,  but  scarcely  up  to  the  best  wet  work. 
It  has  no  great  capacity  for  mastering  contrasts,  because  over¬ 
exposure  causes  a  deep  red  solarization,  obliterating  every  trace 
of  detail.  It  is,  therefore,  necessary  to  be  extremely  careful  to 
avoid  over-exposure.  It  is  probable  that  this  process  would 
work  well  with  a  collodion  containing  bromides  exclusively. 
Filtration  before  each  using  is  necessary.  No  under-stratum  is 
required. 

It  seems  exceedingly  probable  that  the  introduction  of  glyce¬ 
rine  into  the  negative  bath  would  enable  us  to  obtain  plates  that 
would  keep  for  a  long  time,  especially  if  the  method  of  two  baths 
be  adopted,  the  glycerine  used  in  the  second  one. 


CHAPTER  XVI. 

DRY  PLATE  PHOTOGRAPHY. 

» 

Before  describing  specific  processes,  the  writer  proposes  to 
give  such  manipulations  as  belong  to  all  dry  work,  and  which 
need  not  be  repeated  in  connection  with  individual  processes. 
Formerly  it  was  held  that  only  second-class  work  could  be 


352 


PHOTOGRAPHIC  MANIPULATIONS. 


done  with  dry  plates.  But  it  is  now  established  that  soft  and 
delicate  negatives,  full  of  half-tone,  can  be  made  on  dry  plates, 
and  that  in  place  of  the  tedious  and  exaggerated  exposures  needed 
by  the  older  method,  dry  plates  can  be  made  as  rapidly  as  wet. 

$  1.— Preparation  of  the  Glass. 

It  will  be  desirable  to  clean  the  glass  by  the  bichromate  pro¬ 
cess  already  described.  Before  receiving  the  coat  of  collodion, 
they  should  have  an  edging  of  India-rubber  dissolved  in  benzine. 

Procure  some  fresh  clean  India-rubber,  wet  the  blade  of  a 
knife  and  pare  off  the  outside  and  reject  it.  Cut  the  rest  into 
very  thin  strips,  put  about  a  quarter  of  an  ounce  of  it  into  half  a 
pint  of  good  benzine ;  common  benzine  will  not  answer  at  all, 
but  a  pure  specimen  is  needed.  Shake  up  well,  and  in  a  few 
days  solution  will  take  place.  This  solution  may  be  diluted  by 
adding  twice  its  bulk  of  benzine;  it  is  then  ready  for  use.  (It  is 
said  that  moistening  the  strips  of  India-rubber  with  chloroform 
will  aid  the  solution.)  The  writer  has  always  succeeded  in 
making  the  preparation  without  this  aid. 

Tie  a  camel’s-hair  pencil  to  a  glass  rod  of  medium  size  a  little 
way  from  the  end.  Take  a  wide-mouthed  four-ounce  vial,  and 
into  the  cork  make  a  hole  that  will  just  receive  the 
glass  rod.  Into  the  vial  put  the  diluted  rubber  solu¬ 
tion  to  the  depth  of  half  an  inch.  Push  the  glass 
rod  down  so  that  when  the  cork  is  in,  the  rod  will 
touch  the  bottom.  (See  Fig.  132 ;  the  rod  should 
project  about  ten  inches  above  the  cork.) 

When  ready  to  begin,  take  a  plate,  hold  the  glass 
rod  against  its  edge  so  that  the  brush  will  press  on 
the  face  of  the  plate.  Draw  the  rod  round,  and  thus 
make  a  neat  border  an  eighth  of  an  inch  wide  round 
the  plate.  Edge  half  a  dozen  plates  in  this  way,  and 
set  them  in  a  rack  to  dry  (they  dry  immediately) 
before  beginning  to  coat. 

Many  sorts  of  dry  plates  blister — that  is,  the  solu¬ 
tions  penetrate  the  film  and  get  between  it  and  the 
glass,  raising  the  film  into  blisters.  It  is  best,  there¬ 
fore,  to  leave  the  corners  open,  so  that  this  may  have 
a  fair  chance  to  run  out,  or  rather;  it  is  better  to  carry  the  coat¬ 
ing  along  the  longer  sides,  but  leave  a  break  at  the  ends  of  the 


Fig.  132. 


DRY  PLATE  PHOTOGRAPHY. 


353 


Fig.  133. 


shorter  side.  This  allows  the  liquids  to  drain  easily  out  of  the 
breaks  in  the  edging.  (See  Fig.  133.) 

With  plates  larger  than  6J  x  8J,  however,  or  when  the  films 
show  themselves  tender,  it  is  an  excellent  precaution  to  varnish 
the  edges  just  before  developing,  as  well  as 
before  coating.  This  double  application  gives 
great  steadiness  to  the  film,  without  interfering 
with  the  escape  of  any  liquid  which  may  have 
worked  through.  The  writer  has  often  saved 
plates  in  this  way  which  would  undoubtedly 
have  split  without  the  second  edging. 

Some  edge  the  plates  after  exposure,  but  the 
protection  afforded  is  inferior  by  very  much, 
and  the  trouble  fully  as  great.  Some  use 
albumen  as  an  under-stratum  for  the  whole  plate ;  the  method  of 
doing  this  has  been  described  at  page  155.  Others  use  an  under¬ 
stratum  of  thin  solution  of  India-rubber  over  the  whole  plate, 
which  plan  the  writer  does  not  think  well  of. 

The  writer  recommends  always,  when  possible,  to  prepare  dry 
plates  at  night ,  because  at  that  time  the  windows  can  be  kept 
raised  enough  to  thoroughly  ventilate  the  room,  and  so  diminish 
the  injurious  effects  of  the  fumes  of  collodion. 


§  2.— Drying. 

Thorough  drying  is  necessary  for  dry  plates,  and  may  be  effected 
by  spontaneous  drying ,  by  heat ,  or  with  sulphuric  acid . 

Heat. — A  4-sided  vessel  is  made  of  sheet-copper,  in  shape  a 
truncated  pyramid.  A  ledge  at  bottom  keeps  the  plate  in  its 
place.  The  vessel  is  half  filled  with 
water,  and  heat  applied  from  below.  If 
the  water  is  boiling,  or  nearly  so,  the 
plates  will  be  safely  dry  in  twenty-five 
to  thirty  minutes.  They  should  always 
stand  five  or  ten  minutes  to  drain  before 
the  heat  is  applied.  Irregular  surface 
markings,  which  at  one  time  caused  the 
writer  considerable  annoyance,  he  suc¬ 
ceeded  in  tracing  to  this  cause,  and  they  at  once  disappeared 
wholly  by  taking  the  precaution  of  letting  the  plates  stand  and 


Fig.  134. 


354 


PHOTOGRAPHIC  MANIPULATION'S. 


drain.  The  hotter  the  drying  temperature  the  longer  the  plates 
should  wait. 

Drying  by  Sulphuric  Acid. — The  writer  believes  that  much  of 
the  difficulty  experienced  in  making  good  dry  plates  depends 
upon  the  method  of  drying.  The  slow,  even  drying  obtained  by 
placing  the  plates  in  a  tight  box  with  a  pan  of  sulphuric  acid,  as 
recommended  by  him  many  years  ago,  gives  a  remarkably  even 
and  perfect  plate,  and  he  uses  it  exclusively. 

Drying  Box. — After  planning  and  having  made  several  sorts 
of  drying  boxes,  all  of  which  proved  unsatisfactory,  the  writer 
has  contrived  that  shown  in  the  adjoining  figure,  and  which,  after 
full  trial,  has  seemed  to  him  to  leave  nothing  to  desire. 

The  box  (Fig.  135)  has  the  front  hung  on  strap-hinges  so  that 
it  turns  entirely  over  and  rests  on  the  top,  as  shown  in  the  figure. 


When  brought  down,  it  closes  upon  a  rebated  edge,  and  is  secured 
by  the  turn  buttons  T  T.  About  five  inches  from  the  bottom 
are  placed  at  each  end  the  cleats  A  A,  and  at  the  same  level,  the 
bridges  B  B.  On  these  four  pieces  the  rack  (Fig.  136)  slides  in, 
and  when  the  front  is  brought  down  and  secured,  the  rack  is  per¬ 
fectly  protected  from  light.  A  small  door,  D,  permits  the  pan, 
containing  about  a  pound  of  sulphuric  acid,  to  be  slid  in.  This 
door  opens  outwards,  not  inwards,  as  represented  in  the  cut,  by 
an  error  of  the  engraver. 

The  rack  (Fig.  136)  is  constructed  as  shown  in  the  section  (Fig. 
137).  B  B  are  two  long  strips  of  light  wood,  into  these  are  mor- 


DRY  PLATE  PHOTOGRAPHY. 


355 


tised  cuttings  of  thick  plate-glass 
about  half  an  inch  wide,  over  a  quar¬ 
ter  thick,  and  about  seven  inches 
long.  These  are  laid  with  the  flat 
side  against  B  and  are  mortised  in, 
but  not  fully,  so  that  when  the  out¬ 
side  pieces,  A  A,  are  screwed  against 
B  B,  they  hold  the  glass  firmly  in 
its  place,  and  leave  spaces,  E  E. 

Between  each  two  glass  uprights,  these  spaces,  E  E,  extend  all 
the  way  to  the  top.  On  the  pieces  A  A,  strips  of  glass,  0  0,  are 
cemented. 

If  the  reader  will  carry  the  construction  of  this  section  over  to 
the  full  view  (Fig.  136),  he  will  see  that  every  sensitive  plate,  when 
set  in,  is  supported  in  six  places,  and  yet  touches  nowhere  any¬ 
thing  but  glass.  It  leans  back  on  the  two  uprights  behind  it,  at 
the  lower  front  edge  it  touches  the  two  uprights  in  front  of  it, 
and  near  its  corners  it  touches  the  outside  edges  of  the  glass 
strips,  C  C.  It  is  consequently  held  very  securely,  and  also  the 
drainings  are  conducted  away  at  four  different  points  from  each 
plate.  As  the  back  of  the  plate  rests  against  two  points  only 
(the  tops  of  D  D,  Fig.  137),  the  backing  can  be  applied  as  soon 
as  the  plate  is  out  of  the  sensitizing  bath,  and  the  back  and  front 
thus  dry  together,  saving  much  handling. 

In  Fig.  136  the  rack  contains,  for  simplicity,  ten  pairs  of  up¬ 
rights,  accommodating  nine  plates.  In  the  box  used  by  the 
writer  there  are  twenty-five  pairs,  accommodating  two  dozen 
plates  of  any  size,  from  half-plate  up  to  8  x  10.  In  fact,  this 
form  of  rack  has  the  advantage  that  it  will  support  any  size  of 
plate,  and  if  the  box  were  of  suitable  dimensions,  would  contain 
plates  from  half-size  up  to  10  x  12,  or  larger. 

If  the  box  is  not  kept  in  the  dark  room,  it  should  have  a  thick 
black  cloth  cover.  The  writer  usually  leaves  his  plates  in  the 
box  thirty -six  hours  before  using  them,  in  order  to  insure  per¬ 
fect  drying  in  every  part. 

A  simpler  but  less  compact  mode  of  making  a  drying  box  is 
simply  to  take  an  empty  box,  set  a  pan  of  acid  in  the  bottom  and 
a  range  of  empty  tumblers  round  the  sides.  In  each  tumbler  set 
the  lower  corner  of  a  plate,  and  let  the  upper  rest  against  the  side 
of  the  box.  Cover  up  securely  from  light  and  from  change  of 
atmosphere. 


356 


PHOTOGRAPHIC  MANIPULATIONS. 


Drying  spontaneously  is  effected  in  a  dark  cupboard,  or  even  on 
shelves  in  a  dark  room.  Drain  the  plates  for  a  minute  or  two, 
not  more,  on  blotting-paper,  and  then  set  them  in  the  cupboard, 
each  with  the  lower  end  resting  in  an  empty  tumbler,  its  upper 
corner  against  the  wall.  Some  allow  the  plates  to  dry  on  blotting- 
paper  ;  this  has  the  disadvantage  of  keeping  the  lower  end  very 
long  in  drying,  and  so  risking  unequal  action  in  development. 


\  3. — Backing  the  Plates. 

Dry  plates  are  almost  always  more  transparent  than  wet  ones, 
so  that  the  tendency  to  internal  reflection  is  greater  than  with 
wet  plates.  The  result  is  blurring,  otherwise  called  “  halation,” 
and  its  effect  is  that  the  high  lights  work  into  the  adjoining 
shadows.  Thus  the  foliage  adjoining  the  sky  is  more  opaque 
than  it  should  be.  Roofs  of  buildings  shade  off  towards  the  sky. 
Boughs  of  trees,  when  bare  of  leaves  and  projected  against  the 
sky,  are  especially  apt  to  become  blurred,  as  the  light  works  in 
on  both  sides.  These  effects  are  ruinous  to  the  work,  so  that  it 
becomes  advisable  always  to  coat  the  backs. 

After  much  careful  study,  the  writer  has  finally  come  back  to 
annatto  as  combining,  on  the  whole,  more  advantages  than  any 
other  substance  with  which  he  is  acquainted.  It  is,  however, 
essential  to  use  glycerine  with  it,  or  the  whole  coating  will 
gradually  become  everywhere  penetrated  by  fine  cracks.  Quite  a 
small  proportion  of  good  glycerine  will  wholly  remove  this  diffi¬ 
culty.  The  writer  uses  two  fluidrachms  of  thick  syrupy  glycerine 
to  the  quarter  pound  of  annatto  in  lumps.  A  convenient  way  of 
managing  the  mixture  so  as  always  to  have  it  ready  is  the 
following: — ■ 

Provide  a  half-pint  porcelain  bowl  with  cover  and  handle  (to 
be  obtained  from  a  dealer  in  chemical  utensils).  Put  into  it  a 
quarter  pound  of  annatto  with  a  little  more  water  than  necessary 
to  cover  it,  and  set  aside  for  several  days.  The  annatto  will 
soften,  and  can  now  be  easily  worked  into  a  smooth  paste.  Add 
two  fluidrachms  of  glycerine  and  work  it  well  in.  This  mixture, 
if  kept  closely  covered,  will  keep  good  for  weeks,  $nd  if  too 
thick  can  be  thinned  by  stirring  in  water.  As  the  quantity 
diminishes,  add  more  weighed  annatto  in  lumps,  taking  care  to 
add  also  the  proportionate  quantity  of  glycerine.  The  additions 


DRY  PLATE  PHOTOGRAPHY. 


857 


of  glycerine  are  always  to  be  proportionate  to  the  quantity  of 
annatto  added,  and  not  to  the  water.  This  last  will,  of  course, 
be  added  when  needed ;  the  mixture  should,  however,  form  a 
pretty  thick  paste,  and  is  to  be  put  on  liberally. 

The  writer  has  examined  many  other  mixtures.  Gum  may  be 
colored  deeply  by  aniline  brown  or  other  suitable  pigment.  To 
prevent  cracking,  sugar  must  be  freely  added,  so  that  the  quan¬ 
tity  of  sugar  will  be  nearly  up  to  that  of  gum,  say  in  the  pro¬ 
portion  of  three  to  four  by  weight.  But  the  annatto  is  preferable, 
and  in  practice  does  not  cost  more,  as  it  goes  much  further. 

A  round  bristle  brush  as  thick  as  the  thumb  will  be  found 
convenient  for  applying  the  paste.  Bring  it  up  to  within  a 
quarter  of  an  inch  of  the  edge  all  around.  It  should  be  thick 
enough  not  to  run :  annatto  has  much  less  tendency  to  run  than 
mixtures  of  gum,  and  this  is  no  small  advantage. 

When  plates  are  dried  by  sulphuric  acid  or  spontaneously,  the 
backing  may  be  put  on  as  soon  as  they  are  out  of  the  preserva¬ 
tion  bath.  In  drying  by  heat  this  cannot  be  so  well  done,  at 
least  the  heat  has  a  tendency  to  liquefy  the  backing  and  make  it 
run  down. 

The  character  of  the  coat  when  dry  should  be  carefully  tested. 
Not  only  should  it  show  no  tendency  whatever  to  crack,  but  it 
should  resist  perfectly  when  tried  with  the  thumb-nail.  Even, 
however,  if  the  coating  appear  perfect  when  examined  from  the 
back,  it  may  have  separated  in  places  from  the  glass  sufficiently 
to  be  no  longer  in  optical  contact ,  and  from  that  moment  it  is  per¬ 
fectly  useless.  That  it  is  then  useless  not  only  follows  from 
theoretical  considerations,  but  is  abundantly  proved  by  expe¬ 
rience,  as  the  writer  has  seen  in  his  own  work.  If  a  dry  plate, 
after  thorough  drying,  be  examined  in  the  dark  room,  catching 
the  reflection  upon  the  film  side,  it  should  have  a  perfectly  even 
coloration  and  a  certain  dark  look  all  over.  If  it  appears  here 
and  there  lighter  in  spots,  then  in  these  spots  the  backing  is  no 
longer  in  optical  contact,  however  perfect  it  may  seem,  and  the 
film  at  these  spots  is  unprotected  and  liable  to  blur  if  any  cause 
of  blurring  be  present. 

Before  developing,  sponge  off  the  back  thoroughly  with  cold 
water. 


358 


PHOTOGKAPHIC  MANIPULATIONS. 


§  4.— Acid  or  Silver  Development. 

This  is  conducted  in  precisely  the  same  way  as  the  pyrogallic 
development  of  an  ordinary  wet  plate,  except  that  the  silver  is 
added  very  cautiously,  so  as  to  avoid  too  rapid  a  deposit  upon 
the  high  lights.  The  acid  development  of  dry  plates  has,  how¬ 
ever,  almost  wholly  given  way  to  the 

§  5. — Alkaline  Development. 

This  method  shortens  the  exposure  to  one-half  or  one-third, 
giving  at  the  same  time  softer  and  more  harmonious  effects. 

The  first  idea  of  using  alkali  for  the  development  of  dry  plates 
originated  with  Mr.  Borda,  of  Philadelphia.  The  next  steps  in 
it  were  made  by  Mr.  H.  T.  Anthony,  of  New  York.  These 
gentlemen  were  undoubtedly  the  discoverers  of  the  principle  of 
alkaline  development.  Subsequently  it  was  taken  up  in  Eng¬ 
land,  and  gradually  brought  into  its  present  shape  by  Mr.  Glover, 
Mr.  Leahy,  and  especially  Major  Bussell,  who  made  the  discovery 
that  the  development  might  be  controlled  and  restrained  by  add¬ 
ing  a  few  drops  of  solution  of  bromide  of  potassium  to  the  alka¬ 
line  developing  bath.  This  last  discovery  has  given  us  the  means 
of  managing  the  whole  operation  at  pleasure,  and  producing  every 
variety  of  negative,  from  the  most  veiled  to  the  most  transparent. 

Management. — Prepare  the  following  solutions :  Pour  some 
alcohol  into  an  ounce  vial  of  pyrogallic  acid,  and  filter  the  solu¬ 
tion  into  an  eight-ounce  vial,  washing  the  filter  with  alcohol 
until  the  vial  is  full.  This  gives  a  solution  of  nearly  60  grains 
to  the  ounce. 

Take  6  ounces  of  good  clean  flinty  carbonate  of  ammonia,  and 
pour  over  it  enough  warm  water  (not  hot,  hot  water  decomposes 
it)  to  cover  it.  After  standing  an  hour  or  two,*  filter  into  a  quart 
(32-ounce)  bottle,  add  more  water  to  the  undissolved  residue,  and 
so  on  until  the  whole  is  dissolved  in  the  32  ounces.  This  gives 
a  solution  of  about  80  grains  to  the  ounce,  which  must  be  kept 
well  corked. 

Dissolve  bromide  of  potassium  in  water  in  the  proportion  of 
60  grains  to  the  ounce. 

In  commencing  to  develop  a  lot  of  plates,  put  into  a  small  vial 
half  an  ounce  of  the  60-grain  bromide  solution,  and  three- 


DRY  PLATE  PHOTOGRAPHY. 


359 


quarters  of  an  ounce  of  80-grain  carbonate  of  ammonium,  and 
mix  well  by  shaking. 

Next,  for  a  whole  size  (6f  x8J)  plate,  take  a  7x9  porcelain 
pan,  and  put  into  it  4  ounces  of  water.  Add  \  drachm  of  the 
solution  of  pyrogallic  acid,  and  immerse  the  plate  so  as  to  wet 
it  equally  and  avoid  lines  of  unequal  development  when  the 
alkali  is  added. 

Now  remove  the  plate  and  add  to  the  bath  15  to  20  minims  of 
the  mixture  of  bromide  and  carbonate,  mix,  and  return  the  plate. 
The  image  should  rapidly  come  out,  and  when  its  details  are  well 
out,  add,  without  waiting  longer,  half  a  drachm  of  the  carbonate 
of  ammonium  solution.  Density  rapidly  comes,  and  when  the 
plate  has  reached  printing  strength,  fix  it  as  an  ordinary  wet 
negative.  Except  that  with  plates  made  with  a  collodion  con¬ 
taining  bromides  only,  the  fixing  bath  must  be  very  weak,  one 
part  of  hyposulphite  to  fifty  of  water. 

Heat  in  Development. — The  water  used  in  making  the  develop¬ 
ing  bath  should  never  be  cold,  but  rather  of  the  temperature  of 
70  to  80°.  A  higher  temperature  than  this  is  very  useful  in 
case  of  under-exposure.  If  in  the  development  of  a  plate  it  is 
evident  that  it  has  been  considerably  under-exposed,  and  there 
are  other  plates  that  have  had  a  like  exposure,  it  will  be  well  to 
develop  them  in  a  bath  at  about  blood-heat,  or  even  a  little 
warmer.  This  will  be  found  to  aid  materially  in  getting  out  the 
image,  and  will  often  save  plates  that  would  otherwise  be  lost. 
A  little  more  bromide  in  the  developer  will  be  advisable  when 
it  is  used  hot. 

Acid  Development  to  Finish  the  Alkaline. — In  the  writer’s  expe¬ 
rience,  it  is  always  best,  if  possible,  to  finish  the  plate  wholly  by 
the  alkaline  development.  The  results  are  softer  and  more  har¬ 
monious,  and  the  shadows  more  luminous.  Some,  however,  pre¬ 
fer  only  to  bring  out  a  thin  image,  and  then  finish  with  pyro¬ 
gallic  acid  and  silver.  The  writer  does  this  only  when,  from  a 
material  under-exposure,  it  is  impossible  to  get  printing  density 
without  it.  It  should,  however,  be  very  clearly  understood  that 
in  such  cases  it  is  better  to  resort  to  an  acid  development  than  to 
push  the  alkaline  under  circumstances  that  lead  to  fogging. 

If  the  alkaline  development  stops  entirely  (if  it  even  goes  on 
very  slowly,  it  is  best  to  let  it  take  its  time),  it  can  generally  be 
started  again  by  adding  a  little  more  carbonate  of  ammonium. 
But,  after  carrying  this  addition  to  a  certain  point,  it  is  best  to 


360 


PHOTOGRAPHIC  MANIPULATIONS. 


stop.  The  writer  does  not  find  any  good  effect,  but  rather  mis¬ 
chief,  result  from  raising  the  proportion  of  carbonate  over  one 
and  a  quarter,  or  at  most  one  and  a  half,  grain  to  the  ounce. 

If,  then,  the  addition  of  carbonate  has  reached  this  point,  and 
the  development  has  quite  ceased,  it  will  be  well  to  redevelop 
with  acid.  The  first  thing  needed  is  to  wash  the  plate  under  the 
tap,  to  get  the  alkaline  liquid  out  of  it,  which,  in  contact  with 
silver  solution,  would  cause  instantaneous  fog.  Meantime,  suffi¬ 
cient  water  is  placed  in  a  clean  basin,  and  acetic  acid  (No.  8)  is 
added  in  proportion  of  about  one-twelfth  of  the  water  and  mixed 
by  agitating.  Into  this  the  plate  is  put,  that  the  acid  may  remove 
the  last  traces  of  alkali  before  the  silver  is  applied  (if  the  plate  is 
put  into  the  acid  solution  without  previous  washing,  bubbles  of 
carbonic  acid  gas  may  form  under  the  film  and  detach  it,  as  the 
writer  has  seen  happen).  Pyrogallic  acid  and  the  usual  solution 
of  silver  (nitrate  of  silver  10  grains,  citric  acid  15  grains  to  the 
ounce)  are  added  in  very  moderate  quantities  to  the  bath. 


§  6. — Failures  in  Dry  Plate  Operations  common  to  Dry  Plates 

generally. 

Dry  plates  are  much  more  exposed  to  accidents  than  wet,  partly 
because  the  latter  remain  in  the  sensitive  stage  so  short  a  time 
and  are  used  at  once.  There  is  also  in  dry-plate  work  a  greater 
need  of  strict  cleanliness.  Any  operator,  for  example,  who  ever, 
under  any  circumstances,  places  hyposulphite  in  any  vessel  used 
in  any  of  the  operations  other  than  fixing,  actually  invites  failure. 
The  least  trace  of  hyposulphite  in  the  developing  pan  will  cause 
the  development  to  fail.  A  pan  that  has  been  once  used  for  fix¬ 
ing  must  never  be  used  in  any  of  the  other  operations,  neither  as 
a  water  pan  for  soaking  the  plates  before  the  preservative  nor  for 
any  other  use  whatever.  Each  pan  must  have  its  special  use,  and 
be  reserved  for  it. 

Again,  dry  plates  must  never  be  exposed  to  the  air,  especially 
not  the  air  of  a  work-room,  which  may  have  in  it  gases  of  various 
sorts.  The  plates,  both  before  and  after  fixing,  must  remain  in 
tight  boxes,  perfectly  excluding  air  and  dampness,  for  all  damp¬ 
ness  is  destructive  to  dry  plates.  And  as  to  gases,  the  vapor  of 
acetic  acid,  which  is  often  in  the  air  of  the  dark  room,  tends  to 
destroy  the  latent  image.  Sulphur  vapors  of  any  sort  tend  to  fog. 

Another  source  of  trouble  lies  in  wet  tables.  The  bottles  or 


DRY  PLATE  PHOTOGRAPHY. 


361 


other  vessels  resting  on  the  wet  take  np  some,  and  when  turned 
over  to  pour  from,  a  drop  or  two  from  the  bottom  may  run  along 
the  outside  and  fall  unnoticed  along  with  the  contents. 

Keeping. — Although  many  sorts  of  dry  plates  show  good  keep¬ 
ing  qualities,  yet  their  sensibility  in  most  cases  slowly  diminishes, 
so  that  plates  a  month  old  should  have  full  one-half  more  to 
double  the  exposure  of  fresh  ones.  Also,  the  image,  after  ex¬ 
posure,  tends  to  fade  in  the  delicate  details ;  it  is,  therefore,  com¬ 
monly  said  that  the  golden  rule  of  dry-plate  work  is  to  develop 
as  soon  as  possible  after  exposure.  The  same  evening  is  the  best 
time  of  all,  but  generally  two  or  three  days’  delay  will  not  be 
very  important.  For  longer  delays  a  longer  exposure  should  be 
given.  But  it  is  to  be  carefully  borne  in  mind  that,  quite  apart 
from  fading,  the  longer  a  plate  is  kept  after  exposure  the  more 
it  is  exposed  to  adverse  influences  of  all  sorts. 

Errors  as  to  Length  of  Exposure. — This  is  a  serious  source  of 
difficulty  with  dry  plates.  With  wet,  the  first  plate  tried  gives 
a  clear  idea  of  the  character  of  the  day’s  light,  and  the  rest  are 
measured  thereby.  But  with  dry  plates,  all  on  any  one  excur¬ 
sion  must  be  exposed  on  a  venture,  and  there  is  no  criterion  from 
the  first  to  the  rest.  Fortunately,  there  is  a  good  deal  more  lati¬ 
tude  with  dry  plates  than  wet,  and  in  exposing,  it  is  best  to  err 
on  the  side  of  too  much  rather  than  too  little.  Certain  points 
are  of  consequence  to  remember. 

1.  After  midday  the  light  soon  falls  off*,  and  about  three  hours 
before  sunset,  at  some  irregular  time,  the  diminution  begins  to 
be  very  considerable. 

2.  In  the  beginning  of  September  the  light  is  already  materially 
weaker,  and  a  great  allowance  must  be  made  for  its  failing. 
October,  compared  with  May  or  June,  will  need  about  a  triple 
exposure. 

3.  Cloudy  days,  excellent  for  soft  effects,  are  often  deceptive  as 
to  strength  of  light.  With  very  thin  clouds,  the  light  is  some¬ 
times  extremely  powerful.  With  a  grayish  color  in  the  clouds, 
the  light  is  much  weaker. 

4.  Sheltered  places,  partly  under  trees,  receive  a  great  deal 
less  light  than  open  ones ;  the  difference  is  so  much  greater  than 
appears,  that  such  views  are  extremely  apt  to  be  "under-exposed. 

The  Ratio  of  Exposure ,  compared  with  wet  plates,  varies  with 
different  sorts  of  dry  plates,  but  it  must  never  be  forgotten  that 
the  proportion  of  exposure  increases  always  as  the  light  is  fainter. 

24 


362 


PHOTOGRAPHIC  MANIPULATIONS. 


Thus,  a  dry  plate  which  in  a  good  light  needs  a  threefold  expo¬ 
sure,  will  in  a  poor  light  need  four  or  five  times  the  exposure  of 
a  wet  plate  in  the  same  light,  and  in  very  dull,  rainy  weather 
will  scarcely  receive  any  impression  at  all. 

Non-actinism  of  the  Film  varies  greatly  with  different  processes, 
so  that  in  changing  one’s  process,  one  is  apt  to  be  deceived. 
Two  plates  by  different  processes,  looking  equally  dense,  will 
probably  differ  very  much  in  the  printing. 

Irregularity  of  Surface  before  Developing. — This  peculiarity  the 
writer  has  been  able  to  trace  to  the  use  of  too  strong  preservative 
solutions.  Some  films  will  hold  in  them  much  more  solid  matter 
than  others,  and  what  they  will  not  retain  in  them  of  the  solids 
dissolved  in  the  preservative  bath  solution  must  come  up  to 
their  surface  in  drying.  Merely  thinning  a  collodion  with  alco¬ 
hol  or  ether  may  cause  it  to  give  a  thinner  film,  so  that  the 
preservative  in  use  can  no  longer  be  held  wholly  in  the  film. 
Use  more  pyroxyline  or  weaker  preservative,  and  wash  such 
plates  before  developing  them. 

Image ,  after  advancing  awhile)  goes  bach. — Too  much  carbonate 
of  ammonium,  which  never  should  exceed  one  and  a  quarter  grain 
to  the  ounce  of  developing  bath. 

Fogging. — Same  cause.  Also,  too  much  pyrogallic  acid.  Ex¬ 
posure  of  plates  to  deleterious  gases.  Pushing  too  far  the  deve¬ 
lopment  of  under-exposed  plates.  Using  pans  that  have  had 
hyposulphite  in  them. 

Want  of  Detail  in  Shadows. — Under-exposure.  Too  much  bro¬ 
mide  used  in  the  development.  Insufficient  development. 

Surface  Stains. — Drying  by  heat  without  allowing  to  drain  five 
or  ten  minutes  before  applying  the  heat. 

These  stains,  like  the  irregularity  explained  above,  may  depend 
upon  the  preservative.  If  the  preservative  solution  be  pretty 
strong,  and  collodion  not  a  full-bodied  one,  the  film,  as  it  contracts 
in  drying,  may  not  be  able  to  hold  all  the  dry  preservative,  and 
thus  this  will  be  forced  up  to  the  surface  in  places  as  it  dries, 
and  dry  in  superficial  stains.  The  coffee  process  is  subject  to 
this  difficulty.  Eemedy :  Change  the  collodion  or  dilute  the  pre¬ 
servative. 

Want  of  Intensity. — Bad  pyroxyline.  Under-exposure.  Over¬ 
exposure  may  produce  same  result.  In  the  latter  case  the  whole 
picture  flashes  up — in  the  former  the  high  lights  come  easily,  and 
the  rest  very  slowly. 


DRY  PLATE  PHOTOGRAPHY. 


863 


Stains . — Insufficient  cleaning.  Handling  with  dirty  hands,  or 
touching  the  plate  at  all. 

Dampness. — Exposure,  even  temporary,  to  dampness,  gives  rise 
to  more  or  less  decomposition  of  the  sensitive  film,  resulting  in 
insensitiveness  and  other  troubles.  The  writer  invariably ,  in  all 
weathers,  wraps  his  slides  in  waterproof  black  cloth,  using  a 
piece  sufficiently  large  to  cover  them  with  several  folds.  Another 
piece,  about  four  and  one-half  feet  square,  is  again  wrapped  over 
this;  the  latter  serves  as  a  focussing  cloth  also.  Slides,  even 
when  so  wrapped,  should  never  be  laid  on  the  ground  or  on  damp 
stones.  In  a  word,  every  precaution  must  be  taken  to  insure 
dryness  before  and  after  exposure. 

Transparent  Dots  and  Filamentous  Marks. — Dust  in  the  pre¬ 
servative  solutions,  or  falling  on  the  plates  in  the  slides  or  in  the 
camera. 

Blistering. — This  annoying  trouble  depends  upon  the  pyroxy- 
line.  Often  the  sorts  otherwise  the  best,  blister  badly.  Leaving 
open  places  in  the  edging,  that  the  water  may  wash  out,  is  the 
best  remedy.  (See  Fig.  183,  p.  353.) 

Mistakes  in  Exposing. — Nothing  is  more  vexatious  than  to  ex¬ 
pose  by  mistake  a  second  time  a  plate  that  has  been  already  used. 
Every  dark  slide  should  have  a  number  plainly  painted  on  it, 
and  the  slides  should  be  exposed  in  the  order  of  their  numbers. 
Those  who  find  a  tendency  to  mistakes  of  this  kind  may  render 
them  impossible  by  pasting  a  strip  of  paper,  one  end  to  the  slide 
and  the  other  to  the  shutter.  The  exposure  cannot  be  made 
without  breaking  or  cutting  the  strip  previous  to  withdrawing 
the  slide,  and  thus  the  condition  of  the  strip  indicates  at  once 
whether  the  slide  has  been  exposed  or  not. 

Accidental  Uncovering. — If  the  slides  are  carried  far,  and  much 
jarred  or  bolted,  the  shutters  will  sometimes  slip  aside  and  un¬ 
cover  one  end  of  the  plate. 

With  single  dark  slides  the  writer  always  has  a  small  flat  hook 
attached  to  the  slide  and  fastening  to  the  shutter  handle.  With 
double  slides  this  cannot  so  well  be  done,  and  the  best  way  is  to 
tie  twine  round  them. 

Noxious  Fumes. — Any  reducing  vapor  or  gas  must  destroy 
plates.  Sulphuretted  hydrogen,  or  any  foul  emanation  from 
drains  or  water-closets,  chemical  vapors  of  many  sorts,  probably 
also  carbonic  oxide,  the  so-called  “  gas”  that  comes  from  badly 
drawing  stoves.  Sulphurous  acid  would  also  destroy  plates. 


364 


PHOTOGRAPHIC  MANIPULATIONS. 


Resinous  wood  used  for  drying-boxes  or  for  plate-boxes,  or 
freshty-varnished  wood  surfaces  would  be  very  suspicious. 

It  will  be  observed  that  all  of  these  sources  of  trouble  point 
amongst  other  things  to  the  necessity  of  the  complete  exclusion 
of  external  influences.  And  this  can,  perhaps,  in  no  way  be 
better  effected  when  plates  are  to  be  carried  to  any  distance,  and 
preserved  for  any  time,  than  by  inclosing  the  cases  in  thick 
brown  or  dark  green  or  red  paper,  saturated  with  India-rubber 
varnish.  Where  this  cannot  be  procured  commercially,  it  might 
easily  be  made  by  the  photographer  himself.  The  joints  of  the 
paper  must,  of  course,  be  pasted  down  with  the  varnish  also. 


CHAPTER  XVII. 

DRY  PROCESSES. 

In  the  foregoing  chapter  the  writer  has  endeavored  to  group 
together  those  details  that  are  common  to  all  dry  processes. 
Therefore,  before  undertaking  any  of  the  following  methods,  it 
is  presumed  that  the  photographer  has  made  himself  acquainted 
with  its  contents. 

In  learning  any  one  dry  process  a  step  will  have  been  made 
towards  all,  so  much  have  they  in  common.  At  the  same  time 
they  are  nevertheless  very  distinct.  The  best  advice  that  can  be 
given  is  to  hold  persistently  to  some  one  process  until  it  is  com¬ 
pletely  mastered.  Then,  if  desired,  others  can  be  experimented 
with,  with  the  view  of  settling  down  upon  some  one.  It  is  an 
important  matter  to  be  able  to  judge  by  the  inspection  of  a  dry 
plate  whether  it  has  the  right  density  and  modulation  to  print 
well.  This  can  scarcely  be  done  if  the  photographer  changes 
about,  because  some  dry  plates  are  very  non-actinic,  whilst  others, 
equally  dense  to  the  eye,  are  comparatively  very  transparent  to 
the  chemical  rays.  Hence  much  changing  will  lead  to  continued 
mistakes  in  development. 

As,  in  the  writer’s  opinion,  the  collodio-bromide  process  gives 
the  most  sensitive  plates  and  the  softest  negatives,  and  as  these 
plates  are  the  most  easily  and  rapidly  prepared,  it  will  be  placed 
first. 


DRY  PROCESSES. 


865 


§  1. — Collodio-Bromide  Dry  Process. 

The  first  idea  of  adding  nitrate  of  silver  to  a  bromised  collo¬ 
dion.  and  of  thus  dispensing  with  the  negative  bath,  originated 
with  Messrs.  Sayce  and  Bolton,  and  was  by  them  put  into  a  prac¬ 
tical  and  workable  shape.  After  several  years  of  constant  use 
and  experiment,  however,  the  writer  has  been  enabled  to  greatly 
increase  both  the  rapidity  and  the  certainty  of  the  process  by 
radical  changes  made  in  every  p&rt  of  the  mode  of  proceeding,  viz., 
by  introducing  aqua  regia  into  the  collodion,  by  adding  the 
nitrate  of  silver  in  a  state  of  solution,  and  also  by  changing  the 
preservative.  The  tedious  washings  are  done  away  with,  and  a 
better  and  more  sensitive  plate  is  made  with  greatly  diminished 
trouble  and  manipulation. 

The  Pyroxyline. — For  collodion  to  be  used  in  this  process,  a 
very  intense  cotton  is  desirable.  The  best  course  is  to  obtain 
specimens  from  two  or  three  sources,  of  cotton  believed  to  be 
intense,  and  to  try  them,  securing  a  good  supply  of  that  which 
answers  best. 


Formula  for  Collodion. 


i 

Ether . 2  ounces. 

Alcohol . .  .  .  .1  ounce. 

Bromide  of  cadmium . 15  grains. 

Bromide  of  ammonium . 3  “ 

Pyroxyline . 21  “ 


The  two  bromides  should  be  placed  together  in  a  test-tube  or 
flask,  and  dissolved  in  part  of  the  alcohol,  with  heat  if  necessary. 
Previously  dissolve  the  pyroxyline  in  the  ether  and  rest  of  alco¬ 
hol.  Set  the  bottle  in  a  light  warm  room,  where  the  sun  will 
fall  on  it  for  several  hours  a  day.  It  will  be  fit  for  use  in  three 
weeks,  and  be  good  for  three  or  four  months,  after  which  the 
film  is  more  apt  to  be  weak,  that  is,  to  split  in  washing. 

Aqua  Regia. — Put  into  a  stoppered  bottle  an  ounce  of  ordinary 
hydrochloric  acid  and  half  an  ounce  of  ordinary  nitric  acid. 
Stand  in  a  warm  place ;  as  soon  as  the  mixture  takes  an  orange 
color,  remove  it  and  keep  it  well  stoppered. 

Gum  Solution. — Several  different  preservatives  may  be  used, 
but  in  all  the  best,  gum  makes  an  essential  part.  It  should  be 
dissolved  and  kept  in  quantity.  Upon  one-quarter  pound  (avoir¬ 
dupois)  of  good  clean  gum-arabic  pour  six  or  eight  ounces  of  hot 


366 


PHOTOGRAPHIC  MANIPULATIONS. 


water,  stir  well,  and,  after  a  portion  of  gum  has  dissolved,  pour 
the  liquid  on  a  filter,  add  more  hot  water,  and  continue  till  the 
gum  is  got  in  solution  in  thirty  ounces  water.  Take  an  equal 
quantity  of  clear  white  sugar  (one-quarter  pound),  and  dissolve 
this  in  portions  in  the  gum-water  before  filtering.  After  filter¬ 
ing,  add  about  two-thirds  of  a  drachm  of  carbolic  acid,  and  the 
mixture  will  keep  for  a  year  in  perfect  condition. 

As  gum-water  is  very  slow  and  troublesome  in  filtration,  it 
will  be  well  to  use  a  percolator.  (See  Part  V.,  Chapter  II.) 

Sensitizing  the  Collodion. — Measure  out  into  a  graduate  as  much 
collodion  as  is  expected  to  be  wanted,  and  add  to  each  ounce,  in 
hot  weather,  two  drops  of  aqua  regia.  The  easiest  and  safest  way 
to  drop  it  is  to  plunge  a  glass  rod  in  the  acid  bottle,  and  let  drops 
fall  from  the  end  into  the  collodion. 

Weigh  out  ten  grains  (10  grains)  of  finely  powdered  nitrate  of 
silver  (fused  is  best,  but  crystallized  will  do)  for  each  ounce  of 
collodion  taken,  and  place  it  in  a  small  flask.  Measure  some  95 
per  cent,  alcohol  in  a  graduate,  allowing  a  quarter  of  an  ounce  to 
each  ounce  of  collodion  taken.  Pour  about  half  of  this  into  the 
flask  upon  the  nitrate  of  silver,  warm  it  over  a  Bunsen’s  burner 
or  other  gas  flame,  agitating  gently  all  the  while.  As  soon  as 
the  alcohol  boils,  remove  it  and  continue  to  agitate.  In  a  few 
moments  return  the  flask  or  tube  to  the  lamp  till  boiling  recom¬ 
mences.  In  this  way  most  of  the  nitrate  will  dissolve ;  this  is 
poured  into  the  collodion,  and  the  operation  is  repeated  with 
some  more  of  the  alcohol,  leaving  a  little  for  a  third  application. 
All  of  the  silver  will  thus  be  easily  got  into  solution. 

The  addition  of  the  nitrate  solution  to  the  collodion  should  be 
made  in  the  dark  room ;  all  the  previous  operations  may  be  con¬ 
ducted  by  ordinary  light.  In  adding  the  nitrate  solution,  a  little 
should  be  poured  in  at  each  time,  shaking  a  little  between  each. 
The  hot  solution  should  not  go  down  the  sides  of  the  bottle,  but 
straight  into  the  collodion.  On  the  sides  it  might  chill  and  crys¬ 
tallize  a  little. 

Most  of  the  nitrate  dissolves  in  the  first  portion  of  the  alcohol; 
as  soon  as  this  is  all  in  the  collodion,  shake  up  well  for  a  couple 
of  minutes.  After  adding  each  following  portion,  half  a  minute’s 
shaking  will  be  ample. 

A  long  narrow  vial  is  preferable  for  this  operation,  and  should 
not  be  more  than  about  half  full,  otherwise  the  shaking  will  act 


DRY  PROCESSES. 


367 


less  effectually,  and  must  be  continued  longer.  It  is  a  good  plan 
to  keep  the  bottle  robed  up  in  yellow  paper,  to  exclude  all  light. 

After  the  last  addition  has  been  made,  and  the  contents  shaken, 
the  bottle  is  to  be  put  aside.  Too  much  shaking  is  more  likely 
to  do  harm  than  good. 

The  mixture  should  stand  for  a  time  that  depends  somewhat 
upon  the  temperature  of  the  room  and  the  season,  and  may  vary 
from  ten  hours  to  sixteen.  It  is  then  ready  for  use  as  soon  as 
filtered. 

No  more  should  be  made  than  is  intended  to  be  used  up,  and 
the  residues  should  be  rejected.  If  kept  over  about  sixteen 
hours,  there  is  no  certainty  of  the  working  of  the  plates,  whereas, 
when  made  as  here  directed,  they  are  more  uniformly  successful, 
and  free  from  fog  and  stains,  than  are  wet  plates. 

Filtering. — Before  using,  the  sensitive  mixture  will  need  to  be 
filtered  through  a  bit  of  clean  sponge  forced  into  the  neck  of  a 
funnel.  This  should  neither  be  put  in  too  tight  nor  too  loose,  the 
Collodion  should  run  through  in  a  very  thin  stream,  or  a  rapid 
succession  of  drops.  The  mixture  filters  quite  as  easily  as  plain 
collodion,  the  bromide  of  silver  in  suspension  being  apparently 
entirely  without  effect  upon  the  filtration.  In  addition  to  the 
sponge,  the  writer  likes  to  use  a  linen  filter.  A  yard  of  the 
finest  and  closest  linen  is  boiled  for  a  few  minutes  in  a  gallon  of 
water,  with  an  ounce  of  common  crystallized  carbonate  of  sodium. 
It  is  then  thoroughly  washed  out  with  clean  water,  and  left  to 
soak,  then  well  wrung  out  with  clean  water.  This  furnishes  a 
large  number  of  excellent  collodion  filters,  and  one  has  more 
certainty  of  getting  films  free  from  specks  when  this  is  used  in 
addition  to  the  sponge. 

Coating  the  Plate. — More  care  is  necessary  than  in  ordinary 
coating,  as  the  collodion  has  more  tendency  to  set  unevenly. 
Pour  on  in  the  same  way  as  usual,  but  without  sending  back  to 
the  far  corner,  put  on  plenty,  cover  the  plate  rapidly.  Raise  the 
far  end  of  the  plate  as  little  as  possible ,  just  enough  to  enable  the 
surplus  to  drain  off.  Keep  it  so,  and  rock  steadily.  In  ordinary 
coating,  at  the  end  of  the  draining  we  raise  the  plate  almost  ver¬ 
tically  :  this  is  exactly  what  is  not  to  be  done  here,  the  plate  is 
kept  almost  horizontal  until  the  collodion  has  set. 

Operating  in  this  way,  if  we  do  not  get  an  even  plate  the  mix¬ 
ture  is  too  thick  and  will  require  to  be  diluted.  This  may  be 
done  either  with  plain  collodion  or  with  ether.  Generally  the 


368 


PHOTOGRAPHIC  MANIPULATIONS. 


former  is  the  best ;  but  it  must  be  plain  collodion  made  with  the 
same  cotton  :  this  is  essential.  In  hot  summer  weather  the  sen¬ 
sitive  mixture  is  much  more  difficult  to  manage,  and  will  some¬ 
times  need  the  addition  of  ether  before  it  will  work  smoothly. 

It  is  impossible  to  judge  of  the  character  of  the  plate  by  hold¬ 
ing  it  between  the  eyes  and  the  light.  But  if  held  a  little  to  one 
side  of  the  light,  every  slightest  inequality  will  become  con¬ 
spicuous.  A  perfect  plate  will  look  perfectly  smooth,  but  plates 
that  show  only  a  slight  irregular  cloudiness  will  give  perfect 
negatives.  If  the  cloudiness  reaches  a  certain  point,  it  will  be 
liable  to  show  in  the  flat  tints,  sky,  water,  &c.  When  the  cloudi¬ 
ness  reaches  to  a  still  greater  extent,  it  is  liable  to  produce  mottling , 
w'hich  shows  especially  in  the  skies. 

Before  proceeding  to  coat  the  plates,  they  will  need  to  be  edged. 
(See  p.  352.)  As  the  coating  should  not  instantly  follow 
the  edging,  it  is  best  to  edge  half  a  dozen  or  a  dozen,  and  stand 
them  in  a  rack.  Each  plate,  before  coating,  should  be  carefully 
brushed  with  a  broad  flat  brush,  and  a  piece  of  folded  paper 
should  be  interposed  between  the  fingers  of  the  left  hand  and  the 
under  side  of  the  plate,  or  else  a  pneumatic  holder  should  be 
used. 

As  soon  as  the  plate  is  set,  it  is  thrown  into  a  pan  of  water  and 
lies  there  until  it  no  longer  shows  greasy  marks  when  taken  out, 
but  exhibits  a  perfectly  uniform  surface.  It  is  best  to  have  three 
or  four  pans  of  water,  and  coat  a  plate  for  each  in  succession, 
agitating  the  pans  gently  from  time  to  time.  As  soon  as  they 
cease  to  show  greasy  marks  and  are  smooth,  they  are  ready  to 
transfer  into  the  pans  of  u  preservative.”  In  these  they  remain 
from  five  to  eight  or  ten  minutes,  at  the  convenience  of  the 
operator.  The  time  is  not  very  material,  provided  it  is  not  less 
than  five  minutes  nor  much  over  ten. 

If  the  plates  are  not  to  be  dried  by  heat,  they  may  be  backed 
at  once.  The  plate  is  taken  out  of  the  preservative  bath,  reared 
on  end,  and  the  back  wiped  with  blotting-paper,  because  if  the 
wet  is  left  on,  it  thins  the  backing  too  much.  The  colored  paste 
(see  p.  356)  should  be  as  thick  as  possible  to  manage ;  it  is 
put  on  thickly  and  carried  up  to  within  an  eighth,  or,  at  least,  a 
quarter  of  an  inch  of  the  edge. 

If  they  are  to  be  dried  by  heat,  the  backing,  if  applied  first, 
will  be  apt  to  liquefy  and  run. 


DRY  PROCESSES. 


369 


When  plates  are  to  be  dried  by  heat,  they  should  drain  five  or 
ten  minutes  before  the  heat  is  applied,  or  surface  markings  may 
be  expected. 

Preservatives. 

Almost  any  preservative  that  can  be  used  with  common  dry 
plates  made  with  a  bath,  can  be  used  also  with  collodio-bromide 
plates. 

The  writer  of  this  manual  has  devoted  a  great  amount  of  time 
to  investigating  the  qualities  of  a  great  range  of  substances  as 
preservatives.  He  finally  adopted  two  as  being  superior  to  any 
of  those  previously  proposed  or  used.  These  are,  first,  pyrogallic 
acid ;  and  second,  a  special  preservative  made  from  cochineal. 

Pyrogallic  Preservative. 

The  writer  uses  for  all  purposes  in  which  pyrogallic  acid  is 
employed,  a  solution  made  by  pouring  alcohol  into  an  ounce 
bottle  of  pyrogallic  acid  till  it  reaches  the  neck.  A  bottle  hold¬ 
ing  just  8  ounces  (or  marked  with  a  diamond  on  the  side  at  the 
point  to  which  8  ounces  fill  it)  is  adopted  for  regular  use,  and 
the  above  strong  solution  placed  in  it.  More  alcohol  is  poured 
into  the  original  pyrogallic  acid  bottle  to  rinse  it,  and  this  is 
poured  upon  the  filter  and  so  on,  till  the  filtrate  amounts  to  8 
ounces.  This  is  the-  simplest  mode  of  operating  and  avoids  all 
waste  of  material,  as  both  the  bottle  and  filter  are  well  washed 
out.  Shake  well  to  mix  the  different  portions. 

To  make  the  pyrogallic  preservative,  take 

Of  above  solution . 1  drachm. 

Of  gum  and  sugar  solution,  already  described  (p.  365)  10  drachms. 

Of  water . 6  ounces. 

In  making  a  batch  of  plates,  it  is  convenient  to  prepare  three 
such  baths  to  save  time,  as  the  plates  are  rapidly  worked  through. 
Each  plate,  as  soon  as  set,  is  slid  into  a  pan  of  water ;  as  soon  as 
the  oily  appearance  is  gone,  it  goes  into  the  preservative  bath, 
and  then  in  five  minutes  is  ready  for  drying.  'Both  the  water 
pans  and  the  preservative  pans  should  be  occasionally  agitated  a 
little  by  lifting  one  end  and  letting  the  liquid  pass  in  waves  over 
the  plate. 

The  writer  has  never  been  in  the  habit  of  making  more  than 


870 


PHOTOGRAPHIC  MANIPULATIONS. 


six  or  eight  plates  in  one  bath.  Using  three  baths,  and  making 
a  batch  not  exceeding  two  dozen  plates,  there  will  have  been 
eight  to  each  bath. 

If  the  plates  are  to  be  dried  without  heat,  it  is  always  most 
convenient  to  back  them  as  already  described,  as  soon  as  they 
are  out  of  the  preservative  bath. 

Cochineal  Preservative. 

Grind  one  and  a  half  ounce  of  good  clean  cochineal  in  a  mor¬ 
tar  with  one  fluidounce  of  fuming  sulphuric  acid.  As  the  paste 
gets  gradually  thicker,  add  more  acid,  until  in  all  two  fluidounces 
have  been  added.  When  well  mixed,  transfer  into  a  wide-mouth 
bottle,  wipe  the  neck  clean  inside,  set  in  a  vessel  of  hot  water, 
and  leave  till  cold.  Let  it  stand  for  a  week,  then  pour  out  into 
about  a  quart  of  water.  Add  slaked  lime  until  a  piece  of  litmus 
paper  dipped  into  the  solution  turns  blue.  Then  filter  and  pour 
water  upon  the  filter  until  the  filtrate  amounts  to  eighty  ounces. 
Add  a  quarter  of  an  ounce  of  carbolic  acid,  and  the  mixture  will 
keep  indefinitely.  As  but  little  of  it  is  needed,  one  making  such 
as  the  above  will  be  sufficient  for  a  season’s  work. 

To  apply  it  as  a  preservative,  take  of  the  above 


Solution . 6  drachms. 

Gum  and  sugar  solution  (p.  365)  .  .  .  .10  “ 

Water . 6  ounces. 


This,  placed  in  a  pan  just  large  enough  to  hold  a  plate  of  6J 
by  8  J,  will  make  a  convenient  bath  for  that  size  of  plate ;  or  the 
quantity  may  be  increased  or  diminished  for  larger  or  smaller 
sizes. 

As  to  the  choice  between  these  two  excellent  preservatives,  it 
is  not  easy  to  decide.  The  cochineal  gives  very  dark,  blackish 
plates ;  the  pyrogallic  acid,  light  brown,  not  unlike  wet  plates. 
The  cochineal  gives  the  softest,  the  pyrogallic  acid  the  brightest 
negatives.  The  writer  has  had  much  more  experience  with  the 
cochineal,  having  used  it  exclusively  for  view-taking  through  an 
entire  season,  and  with  great  satisfaction.  He  has  kept  plates  as 
long  as  three  and  a  half  months  in  good  order. 

The  pyrogallic  preservative  he  has  only  discovered  much 
more  lately,  and  cannot  as  yet  report  upon  its  keeping  qualities. 
Judging  by  analogy,  they  ought  to  be  excellent. 

Either  of  these  processes,  by  increasing  the  dose  of  bromide  in 


DRY  PROCESSES. 


371 


the  development,  will  give  more  and  more  contrast  and  absence 
of  deposit  in  the  shadows,  so  that  it  is  easy  in  this  way  to  give 
the  negatives  an  ambrotype  appearance.  For  a  soft  printing 
negative  this  is  not  desirable,  but  this  property  might  be  useful 
in  making  transparencies  for  the  lantern ,  for  which  the  pyrogallic 
process  seems  particularly  applicable — more  so  than  the  other. 

Other  Preservatives  for  the  Author's  Collodio- Bromide  Process. 

As  already  said,  almost  any  preservative  that  will  work  with  a 
common  dry  plate  is  suitable  for  collodio-bromide  plates.  Next 
in  order  of  excellence  to  the  foregoing  the  writer  places  the  Tea 
preservative ,  first  proposed  by  Mr.  Newton.  This  preservative  is 
undoubtedly  superior  to  tannin,  to  coffee,  or  to  gallic  acid. 

In  the  writer’s  hands,  tea  has  worked  better  without  gum  and 
sugar  than  with  them.  It  is  sufficient  to  take  a  tablespoonful  of 
good  black  tea,  let  it  infuse  in  boiling  water  in  a  covered  cup  in 
a  warm  place  for  an  hour  or  two,  filter  and  dilute  until  the  liquid 
amounts  to  eight  ounces.  As  before,  the  plate,  as  soon  as  the 
water  has  rendered  it  smooth  and  uniform,  is  put  into  this  bath 
for  five  or  ten  minutes,  and  then  backed  and  dried.  The  results 
are  good,  but  distinctly  inferior  to  the  foregoing. 

Coffee  Preservative. — Make  a  decoction  of  an  ounce  of  coffee  in 
eight  of  water,  and  filter.  This  preservative  does  best  with  gum 
and  sugar.  To  the  above  quantity,  an  ounce  and  a  half  of  the 
gum  and  sugar  solution  may  be  used. 

Tannin. — In  the  use  of  tannin  a  great  mistake  has  been  gene¬ 
rally  made  by  using  too  much  of  it.  The  writer  prefers — 

Good  tannin . 16  grains. 

Gum  and  sugar  solution . 10  drachms. 

Water . 7  ounces. 

This  is  about  one-eighth  as  much  tannin  as  generally  directed, 
and  gives  much  softer  and  more  harmonious  pictures.  If  a  de¬ 
ficiency  in  brightness  and  density  is  found,  increase  the  tannin. 

j Exposures. 

For  the  author’s  preservatives,  two  first  described,  give  with  a 
good  light  the  same  exposures  as  for  wet  plates  ;  with  an  inferior 
light,  the  exposure  must  be  longer  than  for  the  wet.  For  the 
tea  plates,  give  once  and  a  half  as  long  as  for  the  wet.  For  the 
coffee  and  tannin  plates,  give  twice  as  long  as  for  the  wet. 


872 


PHOTOGRAPHIC  MANIPULATIONS. 


It  will  be  observed  that  through  all  these  various  treatments 
the  writer’s  collodio-bromide  process  gives  much  greater  sensi¬ 
tiveness  than  is  attained  with  the  ordinary  dry  processes  used 
with  the  same  preservative. 

For  Drying,  see  p.  854. 

For  Development,  see  p.  358. 

§  2. — Dry  Plates  made  with  a  Negative  Bath. 

This  is  the  older  way  of  managing  dry  plate  work,  and  for 
those  who  habitually  use  the  wet  process,  and  occasionally  need 
a  dry  plate,  it  is  the  more  convenient.  It  is  also  preferred  by 
many  habitual  dry-plate  workers. 

For  this  method  of  dry-plate  work  the  regular  negative  bath 
suffices,  though  it  is  an  advantage  to  have  it  a  little  more  acid. 
Ordinary  collodions  may  be  used  if  they  are  pretty  old ;  generally" 
they  are  improved  by  adding  a  little  simply  bromised  collodion 
to  them,  or  a  grain  or  two  of  bromide  of  cadmium  to  the  ounce. 

But  they  will  work  still  better  with  a  very  intense  cotton, 
giving  a  porous  and  not  a  skinny  film.  If  made  specially,  the 
collodion  may  be  salted  as  follows : — 


Iodide  of  ammonium 

* 

e 

. 

• 

,  « 

.  2  grains. 

Iodide  of  cadmium 

. 

,  # 

.  2  “ 

Bromide  of  cadmium 

# 

«  « 

.  3  “ 

Add  a  little  tincture  of  iodine  and  keep  in  a  warm  light  room 
for  several  week.  If  the  pyroxyline  has  a  good  deal  of  intensity, 
it  may  be  used  sooner,  but  age  and  ripeness  have  much  to  do 
with  success  in  dry  plates. 

The  plate  should  be  edged  with  rubber  solution,  as  described 
at  p.  352,  remembering  that  the  collodion  must  not  be  poured 
on  till  the  edging  is  dry.  When  set,  the  plate  is  to  be  slid  into 
a  pan  of  water  until  the  greasiness  disappears,  and  is  next  to  be 
washed  thoroughly  under  the  tap  until  all  free  nitrate  of  silver 
is  removed.  It  is  then  plunged  into  the  bath  of  preservative, 
whichever  it  may  be  intended  to  use,  and  is  finally  backed  and 
dried,  or  dried  first  and  backed  afterwards. 

The  preservatives  have  been  already  described  pretty  fully 
under  the  head  of  the  collodio-bromide  process,  and  the  manipu¬ 
lation  is  much  the  same  in  both  cases,  except  that,  in  the  present 
case,  the  work  is  much  more  laborious.  The  collodio-bromide 


DRY  PROCESSES. 


373 


plate  was  put  into  the  pan  of  water-  immediately  after  coating, 
whereas  the  present  sort  must  first  be  sensitized  in  the  nitrate 
bath.  Again,  the  collodio-bromide  plate  goes  direct  form  the 
water-pan  into  the  preservative,  whereas  the  ordinary  dry  plate 
requires  a  thorough  washing  under  the  water  faucet  to  be  inter¬ 
posed  between  these  two  operations. 

Thus  it  requires  twice  the  time  and  trouble  to  prepare  an  infe¬ 
rior  and  less  sensitive  plate. 

Pyrogallic  Preservative.  See  p.  369. 

Tea  Preservative. 

Tannin  Preservative. 

Coffee  Preservative. 

Clove  Process. 

The  writer  has  found  that  a  preservative  of  cloves  gives  most 
excellent  plates.  Clove  nuts,  not  the  ground  cloves,  are  taken 
and  broken  up.  Over  a  quarter  pound,  pour  a  quart  of  hot  water, 
and,  after,  some  hours,  filter.  To  seven  ounces  of  water  add  one 
ounce  of  this  decoction  and  one  hundred  grains  of  gum.  Treat¬ 
ment  in  all  respects  the  same  as  with  tannin. 

A  decoction  of  Malt  is  with  some  a  favorite  process. 

Resin  Process. 

Despratz  first  showed  that  if  common  rosin,  or  some  other 
sorts  of  resin,  be  added  to  the  collodion,  the  plates  need  no  pre¬ 
servative,  but  may  be  simply  washed  and  dried,  after  going 
through  the  negative  bath.  At  first  the  process  was  much  ob¬ 
jected  to  on  the  ground  that  it  rapidly  deteriorated  the  negative 
bath.  But  it  appears  that  this  may  be  easily  restored  to  working 
order  by  adding  a  thirty-grain  solution  of  permanganate  of  potas¬ 
sium  until  the  bath  retains  a  faint  reddish  coloration ;  then  filter 
and  acidulate.  The  collodion  should  be  of  an  intense  character 
and  porous  structure,  and  to  it  is  added  two  grains  to  the  ounce 
of  common  rosin,  or  one  grain  rosin  and  one  grain  Canada  balsam. 
After  passing  through  an  ordinary  nitrate  bath,  wash  it  tho¬ 
roughly.  It  is  advisable  to  use  distilled  water  for  the  first  and 
last  washings.  The  plates  are  more  sensitive  when  newly  pre¬ 
pared  than  after  keeping. 

Development  same  as  tannin;  or  a  weak  iron  development. 


See  p.  371. 


374 


PHOTOGRAPHIC  MANIPULATIONS. 


Morphia  Process. 

By  Bartholomew.  Said  to  be  more  sensitive  than  many  other 
processes.  Proceed  exactly  as  in  the  tannin  process,  bnt  make 
the  preservative  bath  a  solution  of  acetate  of  morphia ,  one  grain 
to  the  ounce.  The  writer  has  found  it  advantageous  to  add  to 
the  bath  acetic  acid  No.  8  (Beaufoy’s),  two  or  three  minims  to 
the  ounce.  Plates  keep  only  from  five  to  twelve  days. 


Gum  Gallic  Process. 


Gordon  recommends  for  collodion : — 


Alcohol  and  ether,  each 
Iodide  of  cadmium 
Bromide  of  cadmium 
Iodide  ammonium 
Pyroxyline,  not  over 


£  ounce. 
3  grains. 
3  “ 

1  grain. 
6  grains. 


Negative  bath  forty  grains.  Leave  in  ten  to  fifteen  minutes  ; 
plunge  into  two  successive  baths  of  distilled  water ;  leave  two 
hours  in  a  third.  Or  use  four  successive  pans. 


Preservative  Bath. 

Water  (warm) . 8  ounces. 

Gum-arabic . 160  grains. 

Sugar  candy . 40  “ 

Gallic  acid . 24  “ 

It  is  advised  to  apply  a  substratum  of  albumen,  and,  before 
developing,  to  edge  with  India-rubber.  Probably  edging  at  first 
with  India-rubber  would  be  sufficient. 

Development  may  be  either  alkaline  (managed  as  in  the  tannin 
process),  or  an  iron  developer  containing  two  grains  of  gelatine 
to  the  ounce  of  developer  may  be  employed.  The  gelatine  should 
be  first  dissolved  in  the  acetic  acid.  A  redevelopment  with  acid 
pyro  and  silver  is  needed.  Fix  in  hyposulphite.  Exposure  three 
times  as  long  as  for  the  wet.  Should  the  alkaline  developer  veil, 
use  more  bromide  in  it,  adopting  the  proportions  given  for  col- 
lodio-bromide  plates. 


NEGATIVE  VARNISHES. 


375 


CHAPTER  XVIII. 

NEGATIVE  VARNISHES. 

It  is  of  the  very  highest  importance  to  the  photographer  to 
obtain  a  varnish  as  nearly  perfect  as  possible.  Upon  it  he  must 
depend  for  the  preservation  of  all  his  work,  and  it  would  be 
difficult  to  adequately  describe  the  losses  that  some  have  suffered 
in  consequence  of  trusting  their  negatives  to  varnishes  of  a  de¬ 
fective  character. 

This  consideration,  and  the  very  contradictory  nature  of  the 
opinions  held  by  good  judges,  have  led  the  writer  of  this  manual 
(although  fortunate  enough  in  his  own  case  never  to  have  used  a 
bad  varnish)  to  undertake  a  very  thorough  and  careful  study  oi 
the  subject  within  a  short  time  past.  The  results  which  were 
reached  proved  not  only  very  important,  but  were  to  a  consider¬ 
able  extent  contrary  to  opinions  which  have  obtained  general 
acceptance,  and  which  had  been  up  to  that  time  entertained  by 
the  author  himself. 

Five  different  varnishes  formed  the  subject  of  this  study,  each 
one  of  a  sort  that  has  been  highly  recommended.  One  was  a 
bleached  lac  varnish ,  two  were  of  unbleached  lac,  one  of  sandarac ; 
these  four  were  spirit  varnishes.  To  these  was  added  a  benzole 
varnish ,  and  as  the  writer  has  never  been  in  the  habit  of  making 
benzole  varnish  for  his  own  use,  a  commercial  benzole  varnish 
was  selected,  of  a  high  character  and  largely  used.  The  four 
spirit  varnishes  were  made  by  the  following  formulae : — 


Ho.  1. — Bleached  Lac  Varnish. 


Bleached  lac,  best  quality  . 

. 

. 

. 

.  9  ounces. 

Sandarac  .... 

.  3  “ 

Essence  lavender 

. 

. 

.  5  “ 

Alcohol  .... 

Filter. 

• 

• 

• 

.  69  “ 

Ho.  2. —  Unbleached  Lac  Varnish 


Orange  lac,  best  . 

Sandarac 

. 

. 

. 

.  80  “ 

Essence  lavender 

. 

. 

. 

\  ounce. 

Alcohol 

. 

. 

.  4  ounces. 

All  the  ingredients  mixed  at  once. 


376 


PHOTOGRAPHIC  MANIPULATIONS. 


No.  3. —  Unbleached  Lac  Varnish. 


Best  orange  lac 

.  .  .  200  grains. 

Alcohol  .  .  •  . 

Dissolve,  filter,  and  add 

Sandarac . 

.  .  .  80  grains. 

Essence  lavender  .... 

fluidrachm. 

Filter  again. 

No.  4. — Sandarac 

Varnish } 

Sandarac . 

.  10  ounces. 

Canada  balsam  .... 

1  fluidounce. 

Essence  lavender  .... 

2  ounces. 

Alcohol . 

.  64  “ 

No.  5  was  the  commercial  benzole  varnish  before  mentioned, 
and  of  which  the  writer  has  not  the  formula. 

These  varnishes  were  applied  on 

waste  negatives  with  heat 

before  and  after,  and  exhibited  the  following  characteristics : — 

Smoothness. — Nos.  1,  3,  5,  perfectly  smooth ;  4  was  somewhat 
thready  and  more  difficult  to  work  ;  2  a  little  irregular,  but  less 
.so  than  4. 

Clearness. — Excepting  that  5  showed  a  very  slight  tendency  to 
dry  dead,  all  were  perfectly  clear. 

Hardness. — This  important  quality  was  tested  by  rubbing 
steadily  with  a  moderately  soft  lead-pencil,  in  one  place,  until 
the  film  was  cut  through,  and  noticing  how  much  resistance  each 
exhibited.  It  was  found  necessary  to  make  this  test  with  great 
care,  as  one  and  the  same  film  varied  much  in  different  parts, 
resisting  best  always  where  the  image  was  densest  (because  there 
was  more  varnish  absorbed  and  retained  there).  It  was,  there¬ 
fore,  necessary  to  choose  a  portion  of  each  of  equal  density,  and 
to  repeat  the  trial  many  times  to  avoid  error.  Result:  No. 4  the 
hardest  and  No.  5  the  softest  by  a  good  deal,  the  rest  inter¬ 
mediate.  No.  3  was  harder  than  1  and  2,  evidently  because  of 
the  more  sandarac  and  less  lavender.  It  was  estimated  that  No.  4 
resisted  four  times  as  much  friction  as  No.  5;  that  No.  2  was 
half-way  between.  No.  3  was  intermediate  between  2  and  4,  and 
No.  1  was  next  in  softness  to  No.  5. 

Resistance  to  Heat. — The  amount  of  resistance  to  heat  exhibited 
by  a  varnish  is  of  very  great  importance.  In  our  hot  summer 
weather  negatives  in  the  direct  rays  of  the  sun  may  become 


1  For  this  formula  the  writer  is  indebted  to  Mr.  Fennemore. 


NEGATIVE  VARNISHES. 


377 


greatly  heated.  It  is  a  fact  well  established  in  physics,  that  glass 
allows  the  heat  rays  direct  from  the  sun  a  much  freer  passage 
than  the  dark  rays  returning  from  an  object  beneath  the  glass. 
Therefore  there  is  a  tendency  for  the  heat  to  accumulate  in  the 
film,  paper,  and  packing,  and  thus  to  subject  the  varnish  to  a 
most  severe  trial.  If  it  softens  in  the  least,  adhesion  of  the  paper 
takes  place,  and  the  negative  may  easily  be  destroyed. 

In  order  to  subject  the  varnishes  in  question  to  a  decisive  test, 
they  were  placed  on  a  metal  vessel  filled  with  hot  water,  and 
heat  was  applied  below  till  the  water  boiled.  From  time  to  time- 
slips  of  paper  were  pressed  forcibly  upon  the  varnished  surface, 
and  then  were  gently  raised  to  observe  if  the  slightest  adhesion 
took  place. 

One  curious  result  observed  was  that  when  the  heat  was  mode¬ 
rately  raised,  Nos.  1  and  2  showed  signs  of  slight  adhesiveness, 
which,  when  the  heat  was  raised  higher,  instead  of  increasing,  en¬ 
tirely  disappeared.  This  evidently  indicated  that,  in  applying  heat 
immediately  after  varnishing,  the  heat  had  not  been  applied  long 
enough  to  drive  off  all  the  essential  oil.  So  that  when,  in  .this, 
experiment,  a  considerable  heat  was  applied,  the  remaining  essen¬ 
tial  oil  softened  the  resins,  but  presently  evaporated,  leaving  the 
film  more  solid.  This  shows  how  much  depends  upon  a  thorough 
application  of  heat  after  varnishing. 

It  was  found  that,  as  all  these  varnishes  were  good,  a  higher 
degree  of  heat  than  that  which  could  be  obtained  by  boiling  the 
water  in  the  vessel  was  necessary  to  decide  as  to  the  superiority. 
Therefore  fresh  pieces  were  taken,  cut  from  the  same  negatives, 
and  these,  without  a  gradual  heating,  as  in  the  former  case,  were 
suddenly  placed  upon  a  piece  of  iron  so  hot  that  a  drop  of  water 
let  fall  on  it  instantly  boiled  away.  This  high  heat  brought  out 
the  differences  in  a  very  decisive  way.  Nos.  4  and  5  were  still 
almost  wholly  free  from  any  tendency  to  stickiness.  Nos.  1,  2, 
and  3  did  decidedly  less  well. 

Resistance  to  Moisture. — When  varnished  films  crack  and  break 
away  in  progress  of  time,  this  evil  generally  results  from  damp¬ 
ness  penetrating  the  film.  Under  its  influence  the  collodion  film 
would  naturally  swell,  the  varnish  not,  and  this  unequal  action 
tends  to  detach  the  film  from  the  glass  and  crack  the  varnish. 
As  this  action  generally  requires  years  to  become  apparent,  it 
was  thought  that  the  most  expeditious,  as  well  as  severe,  test  of 
25 


378 


PHOTOGRAPHIC  MANIPULATIONS. 


resistance  to  moisture  would  be  made  bj  plunging  the  negatives 
under  water. 

Accordingly  pieces  of  the  same  size  in  each  case  were  cut  out 
of  negatives  varnished  with  the  different  varnishes,  applying  the 
same  quantity,  as  nearly  as  possible,  of  each,  and  drying  by  equal 
heat.  These  were  placed  side  by  side  in  a  large  deep  porcelain 
pan  and  kept  covered  with  water. 

At  the  end  of  four  days  No.  5  gave  way  ;  the  rest  were  all  in 
good  order. 

They  were  examined  from  time  to  time,  and  all  appeared  per¬ 
fectly  sound,  until,  at  the  end  of  six  full  weeks ,  it  was  noticed 
that  Nos.  1  and  3  showed  a  very  slight  puckering  at  one  corner, 
as  if  there  might  be  a  commencement  of  detaching.  Nos.  2  and 
4  appeared  to  be  in  as  good  condition  after  six  weeks’  immer¬ 
sion  as  they  were  before  they  were  placed  in  the  pan. 

The  writer  cannot  but  consider  this  result  very  remarkable. 
It  indicates  that,  with  several  of  the  varnishes  of  which  the  for¬ 
mulas  are  here  given,  the  action  of  moisture  amounts  virtually 
to  nothing. 

To  sum  up :  If  we  examine  which  of  all  the  varnishes  ex¬ 
hibited  the  greatest  number  of  good  points,  we  shall  find  it  to  be 
the  much  condemned  sandarac  varnish  (No.  4).  It  was  the  hardest 
in  resistance  to  mechanical  injury,  one  of  the  two  best  resisting  to 
heat ,  and  one  of  the  two  best  resisting  to  moisture.  Its  only  fault 
was  a  tendency  to  threadiness  when  applied,  requiring  a  little 
more  dexterity  to  make  a  good  even  coating. 

The  benzole  varnish  did  not  stand  high  at  all,  its  only  good 
points  being  its  resistance  to  heat ,  in  which  it  was  equalled  by  the 
sandarac,  and  in  hardness,  in  which  it  was  excelled  by  the  same. 
In  resistance  to  moisture  it  was  very  far  behind  all  the  rest. 

The  two  orange-lac  varnishes  (Formulas  2  and  3)  exhibited 
good  qualities.  Number  two  resisted  moisture  for  six  weeks  as 
well  as  the  sandarac.  Both  were  easily  applied,  and  gave 
smooth,  even  films  without  trouble.  But  they  were  deficient 
in  hardness,  and  their  resistance  to  heat,  though  fair,  was  infe¬ 
rior  to  Nos.  4  and  5. 

In  view  of  these  objections  to  the  lac  varnishes,  and  of  the 
very  poor  resistance  of  the  benzole  varnish  to  moisture,  the  pre¬ 
ference  must  evidently  be  given  very  decidedly  to  No.  4,  the 
sandarac,  a  most  excellent  varnish. 


TREATMENT  OF  RESIDUES. 


379 


Varnish  is  generally  best  left  to  clear  itself  by  standing.  It 
quickly  clogs  a  filter,  especially  if  it  contains  lac. 

Varnishes  will  dissolve  some  collodions,  it  is  said,  though  the 
writer  never  saw  this  happen.  In  such  cases  it  is  recommended 
to  add  about  one  or  two  per  cent,  of  water.  The  addition  of 
water,  even  to  a  small  extent,  will  often  diminish  the  solvent 
powers  of  the  alcohol  for  some  of  the  constituent  parts  of  the 
varnish,  and  cause  a  cloud  to  form,  rendering  filtration  necessary, 
and  perhaps  changing  the  character  of  the  varnish.  It  should, 
therefore,  never  be  done  unnecessarily. 

In  view  of  the  results  of  the  above  careful  examinations,  there 
would  be  no  advantage  in  giving  additional  formulae  for  other 
and  comparatively  untried  varnishes,  when  qualities  so  excel¬ 
lent  have  been  proved  to  exist  in  some  of  the  foregoing. 

The  highly  polished  surface  of  a  heat-dried  negative  does  not 
easily  take  color  or  shading.  In  addition  to  the  methods  already 
given  for  overcoming  this  difficulty,  it  may  be  mentioned  here 
that  finely  powdered  resin ,  rubbed  on  the  part  of  the  film  to  be 
operated  upon,  has  been  found  to  be  an  excellent  treatment. 


CHAPTEK  XIX. 

TREATMENT  OF  RESIDUES. 

Every  photographer  should  endeavor  to  avoid  wasting  the 
valuable  metals  that  he  employs,  but  the  extent  to  which  this 
care  should  be  carried  will  depend  largely  upon  the  scale  on 
which  he  carries  his  operations.  It  would  be,  for  example,  a 
waste  of  time  for  the  amateur  to  attempt  to  extract  the  silver 
from  his  hyposulphite  solutions,  but  the  professional  photo¬ 
grapher  should  never  reject  them  without  first  removing  the 
silver,  unless  indeed  he  operates  upon  a  very  small  scale.  But 
the  amateur  will  always  wish  to  recover  the  silver  from  baths, 
positive  a;nd  negative,  that  have  become  useless. 

Eesidues  may  be  worked  in  two  ways,  either  the  dry  or  the 
wet.  Both  are  chemical  manipulations  of  the  very  simplest 
order,  can  be  explained  in  a  few  paragraphs,  and  can  be  readily 
mastered  by  any  man  of  ordinary  intelligence.  The  writer  would 


380 


PHOTOGRAPHIC  MANIPULATIONS. 


recommend  the  professional  photographer  to  use  the  dry  way, 
and  the  amateur,  the  wet. 


§  1. — The  Dry  Way. 

Old  Baths. — These  will  be  thrown  down  with  common  salt. 
Take  good  coarse  but  clean  salt,  make  a  strong  solution  of  it  in 
any  convenient  vessel  of  glass  or  wood.  Pour  in  the  baths  with 
constant  stirring.  Make  sure  that  the  salt  has  been  added  in 
excess,  or  large  quantities  of  silver  may  be  wasted  unknowingly. 
To  make  this  certain,  let  the  whole  have  a  most  thorough  agita¬ 
tion,  then  let  stand  some  hours  to  settle,  take  off  some  of  the 
supernatant  liquid,  and  add  to  it  'a  little  clear  solution  of  salt. 
If  no  precipitate  falls  and  no  cloudiness  is  produced,  the  operator 
may  feel  assured  that  all  the  silver  is  thrown  down  as  white 
chloride  of  silver,  changing  to  violet  whenever  exposed  to  the  air. 

This  chloride  must  next  be  washed.  The  liquid  over  it  is 
carefully  and  completely  drained  off,  clean  water  added  in  abun¬ 
dance,  the  whole  thoroughly  well  stirred  up  and  allowed  to  settle, 
then  poured  off*,  and  this  is  repeated  several  times ;  the  oftener 
the  better.  The  vessel  should  be  capacious,  so  that  the  chloride 
of  silver,  after  settling  for  some  hours,  should  not  form  a  layer 
extending  one-tenth  the  height  of  the  water  in  the  vessel.  (It 
should  be  carefully  borne  in  mind  that  if  any  hyposulphite  baths 
are  poured  into  this,  that,  so  far  from  anything  being  precipitated 
from  them,  the  hyposulphite  will  dissolve  large  quantities  of 
chloride  of  silver,  if  this  has  been  already  thrown  down,  or  pre¬ 
vent  its  precipitation,  if  added  earlier.) 

The  chloride  of  silver,  after  being  washed  and  dried,  is  put  into 
a  crucible,  after  being  mixed  thoroughly  with  half  its  wreight  of 
dry  carbonate  of  soda  and  one-quarter  its  weight  of  clean  sand. 
The  crucible  should  not  be  plunged  suddenly  into  a  hot  fire,  or 
it  will  almost  surely  crack.  But  a  few  live  coals  should  be  put- 
into  the  furnace,  then  a  thin  layer  of  fresh  coal,  then  the  crucible 
on  that,  and  more  fresh  coal  heaped  round  it.  Bring  the  fire 
gradually  up  to  a  bright  red  heat,  and  when  the  silver  is  melted, 
stir  it  up  with  an  iron  rod.  The  most  suitable  crucibles  are  of 
Paris  clay,  to  be  had  of  the  dealers  in  chemical  apparatus.  Com¬ 
mon  sand  or  u  Hessian”  crucibles  are  porous :  if  these  are  used, 
they  should  have  the  pores  filled  up  beforehand  by  fusing  a  little 
borax  in  them,  to  prevent  the  silver  from  sinking  in. 


TREATMENT  OF  RESIDUES. 


381 


Cuttings  and  Spoiled  Prints. — These  should  be  carefully  burned 
in  any  convenient  vessel,  the  ashes  gathered  up,  and  these  may 
be  added  to  the  foregoing.  Some  have  advised  to  heat  the  ashes 
with  nitric  acid,  but  this  does  not  exhaust  all  the  silver,  and  the 
nitrate  of  silver  obtained  is  too  impure  for  use  without  re¬ 
ducing  it. 

Hyposulphite  Baths. — The  silver  is  best  extracted  from  the  old 
fixing  baths,  positive  and  negative,  by  precipitation  with  liver 
of  sulphur  (sulphide  of  potassium).  The  silver  is  thus  thrown 
down  as  sulphide  of  silver.  This  sulphide  of  silver  is  a  heavy 
black  powder,  from  which  the  suipbtiT  is  recovered  by  melting  ^ 1  ‘  ^ 
with  an  equal  weight  of  saltpetre.  But  in  doing  this,  two  pre¬ 
cautions  must  never  be  omitted. 

First,  the  sulphide  must  be  heated  red-hot  by  itself  (that  is, 
before  the  admixture  of  the  saltpetre)  in  an  iron  pot.  The  object 
of  this  is  to  burn  off  the  sulphur  powder  thrown  down  along 
with  the  sulphide  of  silver,  and  which,  if  it  remained  with  the 
sulphide  of  silver  when  melted  with  the  saltpetre,  might  cause 
dangerous  explosions. 

And  secondly,  it  is  necessary  to  be  certain  that  the  whole  of 
the  sulphide  of  silver  is  decomposed.  This  may  be  materially 
aided  by  stirring  the  mixture  after  it  has  been  some  time  fused, 
with  an  iron  rod,  and  continuing  this  for  some  time. 

The  writer,  believing  that  all  photographic  operations  should 
be  carried  on  with  nitrate  of  silver  of  the  best  quality,  not  only 
advises  not  to  mix  the  silver  got  from  the  sulphide  with  that  re¬ 
duced  from  the  chloride,  but  either  to  dispose  of  it  to  a  refiner 
for  further  purification,  or  else  to  purify  it  by  dissolving  it  in 
nitric  acid,  and  adding  this  solution  to  the  spent  baths,  to  be  with 
them  precipitated  as  chloride.  Many  will  doubtless  hold  this  to 
be  excess  of  caution,  but  a  bath,  and  especially  all  negative  baths, 
ought  to  be  beyond  suspicion. 

Gold- Residues. — The  least  troublesome  way  of  managing  them 
is  undoubtedly  that  recommended  by  Davanne,  to  acidulate  the 
spent  toning  baths ;  add  thereto  solution  of  persulphate  of  iron, 
and  to  add  the  precipitate  obtained  by  the  addition  of  the  iron 
solution  to  the  chloride  of  silver,  and  place  them  in  the  crucible 
together.  Then  the  lump  of  silver  contains  the  gold  alloyed 
with  it,  and,  when  the  silver  is  dissolved  in  nitric  acid,  the  gold 
remains  behind. 

The  residue  containing  the  gold,  after  nitric  acid  has  dissolved 


382 


PHOTOGRAPHIC  MANIPULATIONS. 


all  that  it  can  dissolve,  is  a  dark-colored  powder,  which  may  be 
treated  with  hot  nitro-hydrochloric  acid  (nitric  acid  one  part, 
hydrochloric  acid  two  parts),  in  which  it  easily  dissolves. 

§  2.— The  Wet  Way. 

This  method  is  here  recommended  chiefly  for  amateurs  who 
wish  to  work  over  their  positive  and  negative  baths.  A  gallon 
precipitating  jar  is  to  be  about  one-third  filled  with  a  solution  of 
clean  salt,  and  the  baths  are  turned  into  it  and  thoroughly  stirred 
up.  After  the  chloride  has  settled,  and  leaves  the  liquid  clear,  a 
portion  of  it  is  placed  in  a  clean  glass,  and  tested  with  more  solu¬ 
tion  of  salt,  to  make  sure  that  the  precipitation  is  complete. 
After  being  well  washed  by  repeatedly  stirring  up  with  water, 
and  pouring  off  again,  the  water  is  finally  poured  off  closely,  a 
little  sulphuric  acid  is  added,  and  then  a  lump  of  good  zinc. 
For  each  pound  of  silver  an  ounce  of  sulphuric  acid  and  a  half- 
pound  of  zinc  will  be  ample.  The  chloride  rapidly  shows  signs 
of  blackening,  and  this  slowly  proceeds  until  the  whole  of  the 
metallic  silver  is  revived  in  the  form  of  a  grayish-black  powder. 

At  the  end  of  about  two  days,  during  which  the  contents  of 
the  vessel  should  be  occasionally  shaken,  the  operation  will  be 
complete.  The  lump  of  zinc  is  removed,  a  little  more  sulphuric 
acid  is  added,  stirred  up,  and  the  whole  left  for  some  hours. 
The  revived  silver  is  then  washed  precisely  in  the  same  way  as 
the  chloride,  with  eight  or  ten  waters  (first  breaking  it  well  up 
with  the  fingers),  and  is  then  ready  to  dissolve  in  nitric  acid.  To 
effect  this  solution,  place  a  quantity  of  nitric  acid  of  good  quality 
in  a  vessel  of  which  it  does  not  fill  over  one-fifth  or  one-sixth. 
Throw  in  the  silver  powder,  waiting  between  each  addition  till 
the  effervescence  subsides,  and  avoiding  most  carefully  to  inhale 
any  of  the  red  fumes  evolved  ;  to  which  end  the  operation  should 
be  performed  under  a  well-drawing  chimney.  When  all  the 
silver  is  dissolved,  the  solution,  which  is  always  very  acid,  is  to 
be  filtered,  evaporated  down,  and  either  crystallized  or  fused  ; 
the  writer  decidedly  prefers  the  latter. 

In  fusing  nitrate  of  silver,  care  must  be  taken  to  use  a  suffi¬ 
ciently  large  porcelain  basin ;  for  if,  when  the  solution  is  very 
much  concentrated,  it  reaches  nearly  to  the  edge  of  the  basin,  it  is 
liable  to  perform  what  is  known  to  chemists  as  “travelling” — 
that  is,  it  will  creep  over  the  sides,  and  a  crust  once  established, 


VARIOUS  PHOTOGRAPHIC  PROCESSES. 


383 


more  and  more  will  get  over  by  capillary  attraction,  make  a  crust 
on  tbe  outside,  and  run  down,  half  crystallizing  and  half  fused, 
upon  the  table.  The  writer  once  left  a  capsule  with  nitrate  pre¬ 
paring  for  fusion,  for  a  short  time,  and,  on  returning,  found  over 
half  a  pound  outside.  Capsules  of  Berlin  or  Meissen  porcelain 
only  can  be  trusted  for  fusing  nitrate  of  silver. 

This  method  of  operating  gives  satisfactory  results  if  carefully 
carried  out.  The  zinc  used  should  be  pure.  The  Bethlehem 
zinc,  sold  in  the  Atlantic  cities  of  America,  is  excellent  for  this 
purpose.  Granulated  zinc  is  not  near  so  good  for  use  as  zinc  in 
lumps,  for,  though  it  may  work  a  little  faster,  there  is  always 
danger  of  small  portions  being  overlooked  and  remaining  in  the 
silver,  failing  to  be  dissolved  by  the  acid.  The  Bethlehem  zinc 
comes  in  ten-pound  ingots.  Instead  of  granulating  it,  set  it  on  a 
good  fire  till  it  is  nearly  ready  to  melt  at  the  corners ;  remove 
it,  and  it  will  be  found  that,  when  thus  hot,  it  will  break  up 
under  a  hammer  with  the  utmost  facility. 

With  many  photographers  it  will  be  an  object  to  have  as  little 
to  do  with  chemical  manipulations  as  possible.  Such  cannot  do 
better  than  to  sell  their  residues  to  some  fair-dealing  reducer. 
The  residues  should  be  kept  in  good  condition,  and  the  three  sorts 
kept  separate,  viz.,  chloride,  from  throwing  down  old  baths  with 
salt ;  sulphide  obtained  from  fixing  baths  by  precipitating  with 
liver  of  sulphur;  and  lastly,  ashes  from  clippings,  failures,  etc. 


CHAPTER  XX. 

PHOTOGRAPHY  ON  GLASS  AND  ENAMEL,  AND  COLLODIO- 
CHLORIDE  PRINTING. 

§  1. — Printing  on  Glass  by  Development. 

Positives  may  be  obtained  on  glass  in  a  variety  of  ways,  both, 
by  development  and  sun -printing,  and  each  different  method  has 
its  advocates,  and  is  capable  of  giving  good  results.  These  posi¬ 
tives,  when  made  on  ordinary  transparent  glass,  are  known  as 
Transparencies ,  when  printed  on  white  opaque  glass  they  are 
known  as  opal  pictures  or  opalotypes.  The  difference  depends 


384 


PHOTOGRAPHIC  MANIPULATIONS. 


solely  upon  tlie  material  used  as  a  support,  and  either  may  be 
obtained  by  development  or  by  tbe  direct  action  of  sunlight. 

When  made  by  development ,  two  different  methods  may  be  em¬ 
ployed.  An  image  may  be  obtained  in  the  camera,  and  be  sub¬ 
sequently  developed,  or  the  negative  may  be  laid  on  the  sensitive 
plate  and  exposed  to  a  weak  light,  and  followed  by  development. 

Printing  in  the  Camera. — When  it  is  intended  to  print  in  the 
camera,  by  far  the  best  method  is  to  have  a  camera  expressly 
constructed  for  this  purpose,  with  two  bellows  and  two  racks 
and  pinions.  Suppose  the  bottom  of  an  ordinary  camera  to  be 
extended  in  front,  another  camera  to  be  attached,  and  beyond,  a 
frame  to  receive  the  negative.  In  this  way  a  total  exclusion  of 
diffuse  light  is  effected ;  no  ray  can  reach  the  lens  except  through 
the  negative.  The  frame  containing  the  negative  at  the  front  can 
be  racked  in  and  out,  as  also  can  the  dark  slide  and  focussing 
screen  at  the  back ;  the  lens  occupies  a  stationary  position  be¬ 
tween  the  two. 

In  Fig.  138  the  portion  A  receives  the  dark  slide  in  the  usual 
manner.  B  is  similar  to  the  front  of  an  ordinary  camera ;  it  car¬ 
ries  the  flange,  and  into  it  the  lens  is  screwed.  At  1ST  is  a  special 


Fig.  138. 


arrangement  to  receive  the  negative  which  is  to  be  printed.  The 
front,  1ST,  is  raised  and  pointed  at  a  bright  cloud,  or  a  mirror  may 
be  placed  in  front  of  it,  inclined  so  as  to  send  light  from  the  sky 
directly  upon  the  negative,  and  the  focussing  is  done  by  racking 
the  back,  A,  in  or  out.  The  space  from  A  to  B  is  shorter  than 
from  B  to  N,  because  the  centre  of  the  tube  of  the  lens  (which 
projects  beyond  B  towards  N)  should  correspond  with  the  middle 
of  the  base-board.  To  copy  a  whole  size  plate  of  equal  size  with 
the  original,  the  space  from  A  to  N  must  be  fully  four  times  the 
focal  length  of  the  lens  employed.  A  ten-inch  Steinheil  aplanatic 
will  be  useful  for  the  purpose.  In  this  case  the  space  from  the 


VARIOUS  PHOTOGRAPHIC  PROCESSES. 


385 


negative  frame  to  the  focussing  glass  should  be  from  three  feet 
six  to  four  feet.  B  is  stationary.  A  and  1ST  rack  backwards  and 
forwards.  If  the  photographer  has  two  cameras  of  suitable  size, 
they  may  be  combined  so  as  to  give  very  much  the  effect  of  the 
double  camera,  shown  in  the  figure.  The  second  camera  has  its 
lens  removed,  its  front  is  turned  towards  the  front  of  the  other 
camera,  and  the  end  of  the  tube  of  the  one  is  thrust  through  the 
flange  of  the. other.  The  ground  glass  is  also  removed,  the  nega¬ 
tive  to  be  copied  is  secured  in  the  focussing  frame  in  its  place. 

Or  the  arrangement  represented  at  Fig.  139  may  be  used. 
Four  strips  of  wood  extending  from  the  camera  support  a  light 


Fig.  139. 


frame,  in  which  the  negative  is  to  be  secured,  and  during  the 
operation  the  space  between  the  camera  and  the  lens  is  covered 
over  with  a  piece  of  black  muslin  or  a  focussing  cloth.  A  mirror 
placed  in  an  inclined  position  throws  light  through  the  negative. 
The  object  of  arranging  the  legs  as  shown  in  the  figure,  is  to 
admit  of  pushing  the  portion  supporting  the  mirror  outside  of  a 
window,  in  order  to  receive  light  direct  from  the  sky  above.  The 
same  object  may  be  attained  by  nailing  a  board  off  the  proper 
width  and  length  upon  an  ordinary  table,  and  making  it  project 
at  one  end  in  the  same  manner. 

The  larger  the  size  of  the  transparency,  in  proportion  to  the 
original  negative,  the  greater  must  be  the  distance  between  the 
ground  glass  of  the  camera,  and  the  frame  holding  the  negative. 
It  has  been  already  said,  that  when  the  copy  is  to  be  of  the  same 
size  as  the  original,  the  distance  will  be  approximately  four 


386 


PHOTOGRAPHIC  MANIPULATIONS. 


times  the  focal  length  of  the  lens  when  focussed  on  a  distant 
object. 

The  transparency  will  need  to  have  the  same  brilliant  clear¬ 
ness  as  the  negative,  which  will  be  got  in  the  same  way — a  full 
exposure,  a  rapid  development  with  plenty  of  restraining  acid, 
and  fixing  immediately. 

It  is  scarcely  necessary  to  say  that  the  negative  for  this  pur¬ 
pose  must  have  precisely  the  same  properties  as  those  intended 
for  enlargement  (see  p.  177.)  It  must  not  be  dense;  print  must 
be  easily  legible  through  the  densest  parts.  The  deep  shadows 
must  be  represented  by  clear  glass,  free  from  all  trace  of  veiling. 

Contact  Printing  followed  by  Development . — Transparencies  may 
also  be  obtained  by  the  wet  process  without  the  use  of  the  camera. 
A  wet  plate  is  prepared  in  the  ordinary  way,  and  after  thorough 
draining,  strips  of  thin  letter  paper  are  laid  on  its  face  near  the 
edges  where  it  is  not  important  to  get  the  image,  and  the  nega¬ 
tive  is  laid  face  down  on  these,  which  preserve  it  from  actual 
contact.  It  is  then  held  for  half  a  minute  or  thereabouts,  accord¬ 
ing  to  the  density  of  the  negative,  under  an  argand  burner,  and 
development  is  effected  in  the  usual  way.  A  dense  negative  will 
not  answer. 

The  treatment  of  the  positive  after  development  will  depend 
upon  the  object  in  view.  If  the  object  be  to  produce  a  picture  to 
be  viewed  in  the  stereoscope  or  hung  against  a  window,  the  plate 
after  fixing  will  be  blackened  with  corrosive  sublimate,  or,  better, 
will  be  treated  with  iodine  and  then  with  sulphide  of  potassium. 
(See  p.  171.) 

If  the  intention  is  to  produce  an  enamel  by  Griine’s  process 
(which  see),  the  plates  will  be  toned  with  bichloride  of  platinum. 

The  same  results  as  the  above  are  got  by  using  a  dry  plate, 
exposing  under  the  negative  in  a  frame  for  a  few  seconds  to  diffuse 
daylight,  or  for  about  a  minute  under  an  argand  gas-burner,  or  to 
magnesium  light;  the  latter  being  the  most  certain,  as  when  the 
quantity  of  magnesium  required  for  one  operation  has  been  once 
determined,  it  is  easy  to  repeat  without  danger  of  error. 

Transparencies  for  the  Magic  Lantern ,  or  11  Stereopticonf  may  be 
made  in  several  ways.  Contact  printing  on  wet  collodion,  as 
just  described,  may  be  used,  or  they  may  be  printed  on  the 
camera,  as  above,  or  dry  plates  may  be  used ;  the  latter  method 
was  habitually  employed  by  a  photographer  who  for  a  long  time 
supplied  most  of  our  dealers  with  lantern  slides.  Equally  good 


VARIOUS  PHOTOGRAPHIC  PROCESSES. 


387 


results  are  got  by  wet  collodion.  Tn  any  case  the  lights  must  be 
perfectly  transparent.  A  long  exposure,  rapid  and  very  acid 
development,  quick  fixing,  and  then  a  treatment  with  corrosive 
sublimate,  followed  by  cyanide  of  potassium  or  sulphide  of  po¬ 
tassium,  will  be  suitable.  (See  p.  172  for  details.) 

The  Albumen  Process. — The  albumen  process,  which  was  used 
for  making  negatives  before  the  discovery  of  the  collodion  method, 
and  which  was  superseded  by  it,  gives  finer  transparencies  on 
glass  than  any  other  method  in  use.  A  good  deal,  however, 
depends  upon  the  personal  skill  of  the  operator.  It  was,  for  ex¬ 
ample,  long  believed  that  Ferrier’s  magnificent  specimens  were 
produced  by  some  secret  process  of  his  own,  but  eventually  it 
appeared  that  he  used  the  regular  method,  as  follows : — 

The  whites  of  twenty  fresh  eggs  are  taken,  clear  of  yelk. 
Iodide  of  potassium  one  hundred  grains,  and  five  grains  of  iodine, 
are  dissolved  in  a  little  water  and  added  to  the  albumen,  and  the 
whole  is  beaten  up  to  a  froth,  and  set  in  a  cool  place  to  subside. 
As  in  this  process  it  is  of  the  greatest  importance  that  no  dust 
shall  settle  on  the  plates,  it  is  necessary  that  the  operating-room 
should  be  cleaned  the  day  before  by  wiping  off  the  floor,  walls, 
and  woodwork,  with  a  wet  cloth.  Shortly  before  commencing, 
the  floor  is  to  be  sprinkled  with  water. 

A  stout  iron  plate  is  fixed  in  a  horizontal  position  over  a  gas- 
burner,  or  any  other  efficient  lamp.  The  albumen  having  been 
poured  off  perfectly  clear,  is  then  extended  over 
the  plate  (absolutely  clean),  an  operation  which 
is  aided  by  first  breathing  gently  on  it  so  as  to 
let  the  moisture  condense.  Four  silk  cords 
have  each  a  little  hook  at  the  end,  the  other 
ends  are  tied  together  and  held  in  the  hand  ;  the 
hooks  are  slipped  under  the  plate,  which  is  then 
supported  by  the  cords.  In  this  way  it  is  sus¬ 
pended  over  the  hot  plate  and  a  rotating  motion 
is  given  to  the  threads,  which  keeps  the  albumen 
distributed  over  the  plate ;  presently  it  is  dry. 

These  plates  are  stored  away,  and  when  wanted-  for  use  are 
sensitized  in  an  acid  silver  bath  prepared  as  follows: — 

Nitrate  of  silver . .1  ounce. 

Acetic  acid  (glacial) . 2  ounces. 

Iodide  of  potassium . 2  grains. 

Distilled  water  . . 14  ounces. 


Fig.  140. 


388 


PHOTOGRAPHIC  MANIPULATIONS. 


From  a  quarter  of  a  minute  to  a  minute  is  needed  for  sensi¬ 
tizing,  after  which  the  plate  is  rinsed  under  a  tap,  and  laid  in 
fresh  water ;  then  dried  in  any  suitable  way  (p.  353). 

The  exposure  is  made  in  a  suitable  frame  under  a  negative,  for 
a  few  seconds,  to  diffuse  light.  The  development  is  effected  by 
plunging  into  a  bath  of  gallic  acid,  one  grain  to  the  ounce. 
Silver  is  gradually  added  until  the  plate  acquires  the  desired 
density.  Ferrier  is  said  to  have  toned  his  transparencies  by  first 
plunging  them  in  a  weak  sublimate  solution,  and  then,  after 
washing,  into  a  one-grain  solution  of  chloride  of  gold. 

§  2. — Sun-Printing  on  Glass  by  the  Collodio-Chloride  Process. 

Instead  of  developing  a  weak  image  on  glass,  we  may  carry  it 
to  its  full  strength  by  direct  printing.  There  are  two  methods 
usually  employed  for  this  purpose,  the  collodio-chloride  process 
of  Mr.  Simpson,  and  the  albumen  process;  the  first  is  the  easier 
and  most  generally  employed,  the  second  (to  be  described  in  next 
section)  is  more  difficult,  but  gives  richer  effects. 

When  a  collodion  containing  chlorides  only,  instead  of  iodides 
and  bromides,  has  nitrate  of  silver  added  directly  to  it,  the 
chloride  of  silver  which  is  formed,  in  place  of  falling  at  once  to 
the  bottom,  remains  for  a  long  time  suspended  in  the  collodion, 
giving  it  a  milky  appearance.  The  nitrate  of  silver  is  kept  a 
little  in  excess,  and  when  this  liquid  is  coated  upon  glass  or 
paper,  a  surface  is  obtained  which  may  be  printed  upon  very 
much  in  the  same  way  as  albumenized  paper.  (Respecting 
collodio-chloride  on  paper,  see  §  4.) 

•Mr.  Gr.  W.  Simpson,  who  first  proposed  this  method,  directed 
to  make  an  ordinary  plain  collodion  with  equal  parts  alcohol  and 
ether  and  six  grains  of  pyroxyline  to  the  ounce,  and  salt  it  with 

Chloride  of  strontium . .2  grains. 

Citric  acid . 1  grain. 

to  each  ounce,  and  to  sensitize  by  adding  nitrate  of  silver  in 
the  proportion  of  grains  to  each  ounce,  in  fine  powder,  shaking 
up  well. 

Chloride  of  strontium  has  the  advantage  of  easy  solubility  in 
mixed  alcohol  and  ether  (the  chlorides  as  a  rule  are  less  soluble 
in  this  mixture  than  the  iodides  and  bromides),  but  experience 
has  shown  that  it  does  not  give  as  good  a  tone  as  some  other 
chlorides. 


VARIOUS  PHOTOGRAPHIC  PROCESSES. 


389 


The  writer  finds  as  the  result  of  his  experiments  with  this 
process,  that  it  is  better  to  use  considerably  more  pyroxyline  in 
the  collodion  than  six  grains,  especially  when  the  surfaces  are 
not  very  large.  With  glass  plates  of  quarter  and  half  size  fully 
nine  grains  to  the  ounce  may  be  used,  and  the  effects  are  much 
richer  than  with  less  quantities.  He  has  also  found  that  the 
addition  of  carbolic  acid  greatly  improves  the  richness  and  depth 
of  effect,  but  unfortunately  this  treatment  can  only  be  used  with 
collodio-chloride  on  paper;  it  does  not  answer  on  glass,  as  the 
carbolic  acid  separates  out  in  drying  on  glass. 

The  writer  also  finds  it  a  material  improvement  to  dissolve 
the  nitrate  of  silver  in  a  part  of  the  alcohol.  When  put  in  in 
powder,  part  does  not  dissolve.  Some  have  tried  dissolving  the 
nitrate  in  water,  but  this  renders  the  collodion  much  less  manage¬ 
able  and  more  apt  to  give  irregular  films  and  mottled  and  spotty 
effects. 

Dr.  Liesegang  has  lately  published  the  following  formula  : — 


Alcohol  and  ether,  equal  parts . 1  ounce. 

Pyroxyline . 9  grains. 

Chloride  of  lithium . 1  grain. 

Citric  or  tartaric  acid . 2  grains. 

Nitrate  of  silver . 8  “ 


Where  chloride  of  lithium  is  not  to  be  had,  chloride  of  cadmium 
may  be  substituted,  using  twice  the  quantity.  For  pyroxyline, 
Dr.  Liesegang  recommends  one-half  of  his  pyroxyline  and  one- 
half  ordinary  soluble  cotton.  He  shakes  up  the  nitrate  of  silver 
in  crystals,  and  at  the  end  of  a  day  removes  the  undissolved  part, 
powders  it  in  a  mortar,  and  returns  it. 

The  author  recommends  to  dissolve  whichever  chloride  is  used 
in  half  the  alcohol,  adding  to  it  the  ether,  and  dissolving  in  the 
mixture  the  pyroxyline.  The  powdered  nitrate  of  silver  is  to 
be  put  into  a  large  test-tube  or  small  flask,  and  the  alcohol  added 
in  separate  portions  and  boiled.  In  this  way  the  nitrate  is 
speedily  got  into  solution,  and  this' solution  is  poured  into  the 
collodion  and  shaken  up.  Operating  in  this  new  way,  all  the  diffi¬ 
culties  encountered  of  having  the  chloride  of  silver  to  fall  in 
clots  are  done  away  with,  and  a  clear,  smooth  emulsion  is  ob¬ 
tained,  which  keeps  in  excellent  order  for  weeks. 

The  author  has  obtained  good  results  with  fused  chloride  of 
calcium  in  the  collodion,  instead  of  chloride  of  lithium  or  cad¬ 
mium.  Of  the  calcium  salt,  one  and  a  half  grain  to  the  ounce 


890 


PHOTOGRAPHIC  MANIPULATIONS. 


of  collodion  will  be  proper,  and  eight  grains  of  nitrate  of  silver. 
With  chloride  of  calcium,  tartaric  acid  must  not  be  used,  or  a 
gradual  precipitation  takes  place  which  ruins  the  collodion. 

To  keep  the  film  from  slipping  from  the  glass,  edge  it  with 
India-rubber  dissolved  in  benzine,  as  described  for  dry  plates 
(see  p.  852),  or  with  albumen,  but  in  neither  case  should  the  ap¬ 
plication  extend  beyond  the  edges,  a  full  substratum  is  injurious. 
Print  till  the  shadows  are  bronzed,  but  not  too  deeply,  remem¬ 
bering,  however,  that  an  under-printed  plate  is  wholly  worthless, 
whilst  an  over-printed  one  can  be  reduced  by  using  a  stronger 
fixing  solution  and  leaving  longer  in  it.  Tone  in  any  gold  toning 
bath,  using  it  very  weak. 

To  fix,  leave  for  five  minutes  in  a  weak  fixing  bath,  one  and  a 
half  ounce  of  hyposulphite  to  the  pint  of  water. 

M.  de  Constant  first  proposed  fuming  the  plates,  and  certainly 
they  print  more  quickly  and  deeply  when  so  treated.  The  ques¬ 
tion  whether  fuming  is  necessary  will  depend  very  much  on  the 
character  of  the  cotton.  When  a  deep  tone  cannot  easily  be  got, 
fuming  will  be  found  to  help.  Remove  the  stopper  of  an  am¬ 
monia  bottle  and  pass  the  plate  a  few  times  over  the  mouth. 

Special  frames  are  made  for  printing  on  glass  which  permit  of 
examining  the  print.  The  sensitized  glass  plate  is  held  between 
two  iron  straps  which  are  secured  by  screws.  The  vignetting 
boards  furnished  writh  the  frames  rarely  fit  as  closely  as  they 
should  do.  Any  motion  is  of  course  fatal  to  the  sharpness  of  the 
print,  therefore  the  boards  should  be  well  wedged  up. 

Miniature  Effects  on  Ivory  are  best  got  by  transferring  collodion 
films  to  the  ivory,  the  surface  of  which  is  to  be  prepared  before¬ 
hand  by  polishing  it  with  a  little  fine  cuttle  or  pumice  powder, 
and  then  immersing  for  a  minute  in  a  warm  solution  of  gelatine 
(about  20  grains  to  the  ounce).  The  image  is  printed  on  glass 
first  coated  with  gelatine,  and  then  with  collodio-chloride  (or  on 
enamel  or  collodio-chloride  transfer  paper).  After  toning  and 
fixing  in  the  usual  way,  wash  in  a  few  changes  of  cold  water, 
then  immerse  in  warm,  when  the  film  will  float  off.  (Acidulating 
the  water  with  a  drop  or  two  of  sulphuric  acid  to  the  ounce  will 
facilitate  separation.)  Remove  the  film  to  a  vessel  of  cold  water, 
and  float  on  to  the  prepared  ivory  surface.  (B.  J.  Edwards.) 


VARIOUS  PHOTOGRAPHIC  PROCESSES. 


391 


§  3. — Albumen  Positives  on  Glass. 

Clear  white  of  egg  by  beating  it  to  a  froth,  adding  first  to 
twelve  ounces  of  albumen  a  quarter  of  an  ounce  of  clean,  pure 
sal-ammoniac  dissolved  in  an  ounce  and  a  half  of  water.  Coat 
the  plates,  dry,  and  sensitize. 

The  silver  bath  is  made  by  dissolving  two  ounces  of  nitrate  of 
silver  in  sixteen  of  water,  acidulating  with  acetic  acid. 

When  albumen  positives  on  opal  glass  are  thoroughly  well 
made,  they  exhibit  greater  force  and  more  transparency  of  shadow 
than  collodio-chloride  work.  They  are,  however,  extremely 
slow  in  printing,  and  the  success  of  different  operators  has  been 
very  various. 

Positives  on  glass  appear  to  require  longer  and  more  thorough 
washing  than  negative  glass  work,  to  preserve  them  from  fading. 

§  4. — Collodio-Chloride  Printing  on  Paper. 

The  sensitive  collodio-chloride  mixture  (p.  389)  may  be  coated 
on  paper  instead  of  glass,  and  be  printed  and  toned  in  the  same 
way.  But  as  the  film  is  very  apt  to  detach  itself  from  the  paper, 
this  last  must  be  prepared  with  a  coating  of  gelatine.  The  writer 
has  never  met  with  any  paper  of  which  the  sizing  was  qualified 
to  .take  the  place  of  this  coating,  which  may  be  prepared  as 
follows : — 

Kelson  or  Coxe’s  sparkling  gelatine  .  .  .  400  grains. 

Syrupy  glycerine . £  fluidounce. 

Water . 16  fluidonnces. 

The  gelatine  used  alone  renders  the  paper  excessively  stiff; 
this  led  the  writer  to  experiment  with  glycerine  added,  the  effect 
of  which  is  to  greatly  reduce  the  stiffness.  Sven  with  this  addi¬ 
tion,  however,  the  paper  curls  up  somewhat,  and  therefore,  after 
it  is  quite  dry,  it  should  be  laid  in  press  for  some  time,  and 
comes  out  exceedingly  flat. 

The  annexed  cut  represents  a  piece  of  the  coated  paper  laid  on 
a  convenient  piece  of  thin  flat  board,  provided  with  a  handle  at 
one  corner.  The  two  farther  corners  of  the  paper  to  be  collo- 
dionized  are  secured  with  pins,  the  thumb  keeps  down  one  other 
corner,  whilst  the  fourth  is  left  open,  from  which  to  pour  off  the 


excess. 


392  PHOTOGRAPHIC  MANIPULATIONS. 


Fig.  141. 


It  is,  however,  very  convenient  to  lay  the  paper  on  such  a 
board,  and,  instead  of  pinning  it,  to  fold  up  the  edges  about  an 
eighth  of  an  inch  high,  in  order  to  keep  the  collodion  from  work¬ 
ing  over,  and  especially  from  getting  upon  the  back  of  the  paper, 
which  result  quickly  follows  if  the  collodion  is  carried  all  round 
the  sides  without  turning  them  up. 

The  writer  has  found  that  a  considerable  increase  of  richness 
and  tone  is  got  by  the  addition  of  phenic  ( carbolic )  acid.  To  a 
measured  quantity  of  the  sensitized  collodion  add  about  ten  per 
cent,  of  this  acid,  and  it  will  be  found  that  a  much  richer  tint  is 
produced  than  when  the  carbolic  acid  is  omitted.  This  method 
works  well  upon  paper,  but  not  upon  glass.  The  printing  is 
done  in  the  ordinary  way,  and  the  succeeding  operations  are  the 
same  as  when  glass  is  the  support.  (See  sec.  2.) 

§  5. — Photographic  Enamelling. 

Of  all  forms  of  picture-making,  the  enamel  may  be  considered 
the  most  permanent.  Even  the  carbon  process  is  liable  to  the 
objection  that  the  paper  on  which  the  print  is  made  is  a  very 
perishable  substance,  and  positives  on  glass  by  the  collodion 
process  are  liable  at  best  to  many  injurious  influences  from  which 
an  enamel,  burnt  in  upon  glass  or  porcelain,  is  evidently  free. 

For  reproducing  photographs  in  enamel,  several  ingenious  pro¬ 
cesses  have  been  proposed.  Two  at  least  have  been  worked 
commercially  upon  a  large  scale :  that  of  Lafon  de  Camarsac,  in 
Paris,  and  that  of  Gfrune,  in  Berlin.  Lafon  has  maintained  his  a 
close  secret,  whilst  Grriine,  with  commendable  liberality,  has  given 
his  to  the  public.  It  is  his  that  will  be  here  first  given. 

There  exists  no  difficulty  whatever  in  transferring  a  collodion 
film  to  any  other  support.  For  this  purpose  it  is  best  to  diminish 


VARIOUS  PHOTOGRAPHIC  PROCESSES. 


393 


the  adhesion  of  the  collodion,  by  rubbing  the  glass  beforehand 
with  a  little  wax  dissolved  in  ether;  or,  as  proposed  by  Mr. 
Woodbury,  add  to  the  collodion  two  or  three  drops  to  the  ounce 
of  a  saturated  solution  of  beeswax  in  ether,  which  renders  the 
film  easily  transferred  without  affecting  the  photographic  proper¬ 
ties  of  the  collodion. 

The  operator  prepares  a  glass  collodion  positive,  which  must, 
of  course,  be  a  positive  by  transparency,  and  not  an  ambrotype. 
This  may  be  done  in  several  ways  (for  which  see  the  previous 
sections  of  this  chapter). 

The  next  step  will  be  to  tone  with  weak  solution  of  bichloride 
of  platinum  instead  of  chloride  of  gold ;  wash  and  dry.  Run  a 
penknife  round  the  edges,  plunge  the  negative  in  water,  and 
float  off  the  film.  It  will  be  advisable  to  add  a  little  acetic  acid 
to  the  water ;  acids  tend  to  loosen  films  from  their  supports, 
alkalies  to  increase  the  attachment.  Receive  the  film  on  the 
porcelain  surface,  and,  after  allowing  it  to  dry,  dissolve  out  the 
collodion  film  with  mixed  alcohol  and  ether.  The  image  in  pla¬ 
tinum  will  remain  upon  the  porcelain.  It  then  only  remains  to 
apply  a  suitable  flux,  and  burn  in  the  picture  in  a  muffle.  Griine 
has  not  given  the  composition  of  the  flux  that  he  uses,  but  it  is 
probable  that  Leth’s  flux  will  be  found  satisfactory.  It  is  made 


as  follows : — 

Red  lead . 6  ounces. 

Fine  quartz  sand,  or  pounded  quartz  .  .  .  2  “ 

Borax . 1  ounce. 


Melt  in  a  crucible,  and,  after  cooling,  reduce  the  glass  formed 
to  a  fine  powder.  Strew  this  over  the  plate,  place  in  a  muffle, 
and  raise  the  heat  just  high  enough  to  fuse  the  coat  of  flux  into 
a  transparent  glass  over  the  picture. 

This  process  can  also  be  used  for  producing  designs  in  gold 
upon  glass  or  porcelain.  To  effect  this,  the  positive  is  toned 
with  gold,  thoroughly,  and  the  rest  of  the  treatment  remains  the 
same,  except  that  a  reducing  flux  must  be  used.  Ho  half-tone 
can  be  obtained  in  this  way,  because  the  gold,  no  matter  how 
thin,  exhibits  its  full  metallic  color.  It  easily  acquires  a  brilliant 
surface  by  polishing.  Beautiful  designs  in  gold  of  the  most  com¬ 
plicated  figures,  have  been  burnt  into  porcelain  by  Griine  by  this 
process. 

Those  desiring  further  details  may  consult  the  Photo graphisches 

26 


394 


PHOTOGRAPHIC  MANIPULATIONS. 


Archiv ,  Band  VI.,  346 ;  Photog.  News,  IX.,  457 ;  or  Martin’s 
Handbuch  dev  Email-photo  graphie,  Weimar,  1867. 


§  6. — Photolithography. 

To  be  able  to  tranfer  a  photograph  to  stone  or  metal,  and  to 
print  a  large  number  of  copies  therefrom,  is  evidently  a  most 
valuable  application  of  the  science;  and  this  is  now  accomplished 
in  a  very  admirable  manner. 

It  is  evident  that  the  production  of  half-tone  is  more  difficult 
than  the  simple  obtaining  of  black  and  white,  and  that  different 
means  must  be  employed.  The  processes  therefore  will  be  classi¬ 
fied  under  these  two  different  heads: — • 

A. — PROCESS  GIVING  ONLY  WHITE  AND  BLACK. 

Liesegang"' s  Process. — Liesegang  floats  ordinary  albumenized 
paper  (the  salting  is  not  objectionable)  upon  a  solution  of  chro¬ 
mate  of  ammonium.  Then  exposes  under  a  strong,  clear  negative, 
till  a  strong  image  is  got.  Next  lays  it  against  a  zinc  plate,  and 
passes  through  a  press.  Xext  lays  it,  face  up,  on  cold  water,  till 
the  image  becomes  visible.  Takes  a  clean  sponge,  previously 
cleaned  well  with  chlorhydric  acid  to  get  rid  of  grit,  and  removes 
the  excess  of  ink.  Then  transfers  in  the  usual  way  of  litho¬ 
graphic  transfers. 

Liesegang  attaches  importance  to  the  nature  of  the  ink  used 


for  inking  in  the  zinc  as  above  mentioned.  He  takes — 

Venice  turpentine . 81  ounces. 

Wax . 1  ounce. 

Palm  oil . 1  “ 

These  are  to  be  heated  in  an  iron  pot  until  they  take  fire.  Then 
stir  in — - 

Lithographic  transfer  varnish . 33  ounces. 

Linseed  oil  varnish,  No.  2 . 16^  “ 


B. — PROCESS^  GIVING  HALF-TONES. 

ATbertype.-—  The  older  processes  are  likely  to  be  quite  super¬ 
seded  by  the  albertype,  of  which  the  following  is  the  specifica¬ 
tion  for  the  Trench  patent.  Coat  in  the  dark  room  a  heavy  glass 
plate  with — - 


VARIOUS  PHOTOGRAPHIC  PROCESSES.  395 


Filtered  water .  300  parts. 

Albumen . 150  “ 

Gelatine . 15  “ 

Bichromate  of  potash . 8  “ 


Dry  in  the  dark,  and  then  expose  to  light  through  the  glass ,  care¬ 
fully  protecting  the  other  face  in  order  that  the  hardening  may 
proceed  from  the  bottom  (next  the  glass)  to  the  surface,  and  be 
perfectly  solid.  Half  an  hour  to  two  hours’  exposure.  Coat 
again  with — 

Gelatine . 30  parts. 

Bichromate . 10  “ 

Water . 180  “ 

Expose  under  a  negative,  wash  for  about  fifteen  minutes,  and 
dry.  Then  slightly  wet  it  and  work  it  on  a  lithographic  press  in 
the  ordinary  way  with  ordinary  printing  ink. 


§  7. — Photogalvanography. 

It  has  been  known  for  a  period  of  years  that  when  a  mixture 
of  gelatine  and  bichromate  was  extended  on  glass  and  exposed 
under  a  negative,  all  those  parts  protected  from  the  light  could 
be  made  to  swell  up  by  soaking  the  film  in  water.  Consequently 
the  image  is  produced  in  relief. 

The  writer  of  this  manual  worked  out  the  details  of  a  process 
himself,  and  was  the  first  to  publish  any  practicable  method, 
which  will  be  found  in  full  detail  in  the  British  Journal  of  Pho¬ 
tography  for  February  10th,  1865.  Briefly,  the  process  consists 


in  coating  glass  with  a  film  of — 

Gelatine .  200  grains. 

Water . 4  ounces. 

Cold  saturated  solution  bichromate  of  potash  .  5  drachms. 


When  dry,  expose  under  an  average  negative  to  direct  sun¬ 
light  for  two  to  three  minutes.  Then  leave  in  water  for  aobut 
two  hours,  changing  frequently,  then  let  dry. 

The  surface  may  receive  a  conductor  in  several  ways.  Brush 
over  with  an  ethereal  solution  of  chloride  of  gold,  let  dry,  place 
in  sunshine,  and  apply  a  solution  of  protosulphatc  of  iron.  This 
is  the  writer’s  method  of  gilding  the  film,  which  takes  a  brilliant 
gold  surface,  and  is  then  ready  to  be  plunged  into  the  electrotype 
bath. 

But,  on  the  whole,  the  writer  preferred  to  treat  the  dry  gelatine 


390 


PHOTOGRAPHIC  MANIPULATIONS. 


film  (after  the  bichromate,  of  course,  had  been  thoroughly  re¬ 
moved)  with  alcoholic  solution  of  nitrate  of  silver,  and  then  to 
fog  it  with  pyrogallic  acid. 

By  means  of  the  electrotype  bath,  a  copper  reproduction  of  the 
relief  is  obtained  from  which  to  print. 

Woodbury's  Relievo  Process. — The  above  method  is  evidently 
applicable  only  to  the  reproduction  of  engravings  and  wood-cuts  ; 
negatives  of  natural  objects,  made  up  of  half-tones,  cannot  be  used 
for  it.  Woodbury  ingeniously  avoids  this  difficulty  by  a  very 
valuable  process,  which  has  been  patented. 

It  is  easy  enough,  by  the  process  just  above  described,  to  obtain 
a  reproduction  in  copper  of  a  gelatine  relief  of  objects  containing 
half-tones.  This  reproduction  will  not,  of  course,  have  lines  like 
a  copperplate,  but  will  consist  of  undulating  depressions  and 
elevations.  The  difficulty  lay  in  making  this  to  print.  Mr.  W ood- 
bury’s  idea  was  to  mix  a  little  black  pigment  with  gelatine,  to 
spread  this  over  the  plate,  and  then  with  a  flat  surface  to  remove 
the  excess.  A  piece  of  paper  being  then  pressed  against  the 
plate,  receives  the  remaining  gelatine.  In  the  portions  but  little 
sunk,  there  will  have  been  but  little  pigment,  and  these  will 
print  light,  and  just  in  proportion  to  the  depth  of  the  sunk  por¬ 
tion  will  be  the  blackness  of  the  print. 

Work  of  remarkable  beauty  has  been  executed  by  this  process, 
which  is  applicable  to  printing  on  paper,  glass,  wood,  or  any 
other  surface. 


§  8. — Various  Processes. 

Willis’s  Aniline  Process. — This  process  has  likewise  been  pa¬ 
tented.  The  work  produced  by  it  is  of  rather  a  common  order ; 
its  recommendation  is  its  extreme  facility  and  cheapness. 

Paper  is  impregnated  with  solution  of  bichromate  of  potash,  to 
which  a  little  phosphoric  acid  has  been  added.  After  exposure 
under  a  transparent  positive,  it  is  exposed  to  vapors  of  aniline, 
which  develop  a  grayish  image.  The  print  is  then  merely  fixed 
by  simple  washing.  As  a  positive  affords  a  positive,  plates,  draw¬ 
ings,  &c.,  can  be  copied  without  the  intervention  of  a  negative  or 
the  use  of  a  camera.  The  process  is  carried  on  commercially  by 
the  patentee  in  England. 

Prints  in  Color. — Float  close-grained,  fine  photographic  paper, 
plain  or  albumenized,  on  a  warm  solution  of  gelatine,  six  hundred 


VARIOUS  PHOTOGRAPHIC  PROCESSES. 


397 


and  fifty  grains ;  water,  twelve  ounces ;  bichromate  potash,  three 
drachms;  glycerine,  half  fluidounce ;  letting  the  gelatine  swell 
first  in  part  of  the  water.  Dissolve  the  bichromate  in  the  rest. 
When  the  gelatine  has  well  swelled,  dissolve  it  by  heating,  and 
add  (in  the  dark  room)  the  bichromate  solution.  Dry  the  paper 
in  the  dark.  Expose  briefly  to  direct  sunshine  under  a  positive. 
A  light  picture  results  on  a  brown  ground.  Throw  into  water 
for  thirty-six  hours :  the  whole  disappears,  and  the  back  must  be 
marked  to  distinguish  it.  Now  blot  off  the  exposed  surface  gently 
with  bibulous  paper,  leaving  it  very  moist,  and  rub  on  powdered 
color  with  a  wet  hift  of  cotton.  The  color  adheres  to  the  parts 
protected  from  the  oven,  and  thus  a  positive  results.1 

Yery  pretty  effects  are  obtained  by  laying  on  the  paper  ferns, 
grasses ,  &c..,  and  developing  with  a  green  powder,  “  chrome  green” 
(chrome  yellow  and  Prussian  blue,  sold  ready  mixed  under  this 
name)  answers  very  well.  In  this  way,  positives  of  a  green  color 
are  obtained  at  a  single  operation.  They  are  perfectly  permanent. 
If  the  color  does  not  adhere  on  the  image,  the  exposure  has  been 
too  long;  if  it  adheres  on  the  image,  and  elsewhere  also,  too 
short.  When  the  color  has  been  applied,  hold  the  print  a  few 
moments  under  a  stream  of  water  to  clean  the  whites. 

Printing  Processes  with  Salts  of  Iron. — Most  of  the  salts  of  the 
peroxide  of  iron  are  reduced  by  light  to  the  corresponding  salts 
of  the  protoxide,  with  a  loss  of  one-third  of  their  oxygen.  By 
applying  reagents  which  act  differently  on  the  two  oxides  of  iron, 
this  reduction  is  made  apparent,  and  a  colored  picture  is  pro¬ 
duced.  Thus,  if  red  prussiate  of  potash  be  applied,  all  the  part 
acted  upon  by  the  sun  becomes  blue ;  with  gallic  acid  the  unex¬ 
posed  part  becomes  black,  and  so  on. 

Chloride  of  Iron. — Take 


Perchloride  of  iron . 50  grains. 

Tartaric  acid . 15  “ 

Water . ,1  ounce. 


Expose  under  the  object  itself  or  under  a  transparent  positive. 
Plunge  for  an  instant  in  distilled  water,  and  then  in  a  saturated 
solution  of  gallic  acid,  a  decoction  of  nutgalls,  or  a  mixture  of 
gallic  and  pyrogallic  acids,  according  to  the  time  allowed.  The 

1  This  method  of  operating,  described  by  the  writer  in  the  Philadelphia  Pho¬ 
tographer  for  May,  1865,  has  sinqe  been  published  as  new  in  Berlin,  and,  with 
trilling  alterations,  patented  in  England. 


398 


PHOTOGRAPHIC  MANIPULATIONS. 


impression  is  here  in  ordinary  ink,  gallo-tannate  of  peroxide  of 
iron. 

Oxalate  of  Iron  and  Ammonia. — Exactly  saturate  one  ounce  of 
oxalic  acid  with  ammonia,  add  another  ounce,  and  digest  the 
mixture  with  freshly-precipitated  and  still  moist  peroxide  of 
iron.  The  filtrate,  after  the  liquid  is  fully  saturated  with  per¬ 
oxide,  gives,  by  evaporation  in  the  dark,  large  and  splendid 
green  crystals  of  the  double  salt. 

Paper  is  sensitized  by  floating  in  a  minute  or  two  upon  a  tolera¬ 
bly  strong  solution  of  these  crystals,  seventy  to  one  hundred 
grains  to  the  ounce,  and  dried,  in  which  state  it  will  keep  for  a 
long  time.  Exposed  under  a  negative,  an  almost  invisible  image 
is  obtained  after  a  brief  exposure,  which,  by  ferridcyanide  of 
potassium,  becomes  a  blue  picture.  This  process  is  due  to 
Herschel.  It  has  the  disadvantage  that  it  does  not  give  clean 
whites. 

The  writer  imagined  a  remedy  for  this,  which  has  been  very 
successful ;  it  consists  in  adding  a  little  oxalic  acid  to  the  solution 
of  ferridcyanide,  the  whites  thus  remain  brilliantly  clear.  It  is 
necessary,  however,  to  be  careful  about  putting  the  fingers  into 
the  bath.  The  free  ferriprussic  acid  liberated  by  the  oxalic  acid 
continually  decomposes,  with  production  of  prussic  acid,  in  a 
very  dilute  form,  it  is  true,  but  still  active  enough  to  render  care 
advisable. 


CHAPTER  XXI. 

CARBON  PRINTING. 

\  1. — Introductory  Remarks. 

Carbon  printing,  in  the  form  now  in  use,  has  been  the  result 
of  the  action  of  many  minds,  and  the  honor  of  its  discovery  can¬ 
not  be  ascribed  to  the  ingenuity  of  any  one  person.  It  may  be 
traced  back  as  follows  : — 

The  first  step  was  the  remark  that  paper  imbued  with  solution 
of  bichromate  of  potash,  darkened  when  exposed  to  light.  This 
was  made  in  1839  by  Mr.  Mungo  Ponton. 

The  next  was  the  discovery  that  gelatine,  gum,  and  some  other 


CARBON  PRINTING. 


399 


bodies,  were  rendered  wholly  insoluble  when  exposed  to  light  in 
presence  of  bichromate  of  potash.  This  observation  was  first 
made  by  M.  Becquerel;  subsequently  Mr.  Fox  Talbot  patented 
a  method  of  photo-engraving  based  on  it. 

The  next  idea  evolved  was,  that  the  gelatine,  made  insoluble 
by  light,  might  be  made  to  imprison  particles  of  coloring  matter. 
Thus,  where  light  acted,  these  would  remain ;  where  it  did  not 
act,  they  would  wash  out  by  reason  of  the  solubility  of  the  por¬ 
tion  of  the  film  in  which  they  were  contained.  This  was  an 
important  step,  and  was  made  by  M.  Poitevin  in  1855. 

This  was,  in  fact,  a  carbon  process ;  but  in  this,  and  in  all  the 
efforts  made  for  some  time  subsequently,  the  half-tone  was  ex¬ 
tremely  defective. 

M.  Laborde  seems  to  have  been  the  first  to  perceive  that  the 
action  of  the  sun  was  at  first  superficial,  and  only  by  degrees 
penetrating  through  the  layer  of  gelatine.  Thus  those  portions 
under  the  transparent  parts  of  the  negative  became  deep  black, 
because  the  sun  rendered  the  layer  of  gelatine  insoluble  through 
and  through,  and  so  attached  it  fully  to  the  paper.  But  in  the 
half-tones  this  penetration  did  not  take  place ;  the  action  was 
comparatively  superficial ;  the  lower  part  of  the  film  remained 
soluble,  so  that  the  impressed  portion  above  it  was  undermined 
in  developing,  and  broken  away.  The  only  indications  of  half¬ 
tone  obtained  seem  to  have  been  due  to  inequalities  in  the  paper . 
M.  Laborde,  though  he  perceived  the  evil,  did  not  find  a  remedy 
for  it  except  to  suggest  exposing  from  the  back. 

The  honor  of  devising  the  method  of  transferring  is  due  to 
Mr.  Swan.  He  showed  that  the  true  plan  of  developing  lay  in 
attaching  the  exposed  surface  to  paper  or  other  support,  remov¬ 
ing  the  original  paper  support,  and  so  developing  on  the  under  side. 
Thus  all  the  half-tone  was  excellently  preserved,  and  the  picture 
was  re-transferred  to  another  and  final  sheet  of  paper. 

Details. — Since  the  first'  edition  of  this  manual  was  published, 
the  carbon  process  has  been  somewhat  simplified,  and  is  passing 
more  and  more  into  use  in  England,  where  it  is  better  understood 
than  anywhere  else. 

“Tissue”  for  carbon  printing  is  sold  ready  prepared,  and  is  to 
be  sensitized  by  plunging  into  a  solution  of  bichromate  of  potasb, 
one  ounce  in  thirty  of  water.  If  more  sensitive  paper  is  wanted, 
the  proportion  may  be  increased.  •  As  tissue  so  prepared  is  liable 


400 


PHOTOGRAPHIC  MANIPULATIONS. 


to  spontaneously  "harden,  and  at  best  keeps  but  for  a  day  or  two, 
the  writer  pointed  out  some  years  ago  the  advantage  of  adding 
liquid  ammonia  to  the  bichromate  solution,  whereby  the  sensi¬ 
tive  properties  are  preserved  for  several  weeks.  Lately  this 
method  seems  to  have  come  into  commercial  use. 

After  the  sensitized  tissue  has  been  dried,  which  operation 
must  be  performed  rapidly,  but  not  at  too  high  a  heat,  lest  the 
gelatine  melt  and  run,  it  is  exposed  under  a  negative  ;  the  exposed 
surface  is  next  moistened  and  pressed  against  another  sheet  of 
paper.  With  some  sorts  of  highly  sized  papers,  the  exposed  and 
moistened  surface  of  the  gelatine  will  adhere  without  difficulty. 
Other  paper  will  require  a  coating  of  gelatine,  or  albumenized 
paper  may  be  employed  of  which  the  albumen  has  been  coagu¬ 
lated.  The  adhesion  is  made  complete  by  pressure  with  a  wet 
sponge,  or  a  roller  or  “  squeegee,”  and  then  the  two  papers,  with 
the  layer  of  gelatine  between,  are  thrown  into  water  scarcely 
lukewarm ;  presently  the  original  support  can  be  removed,  and 
the  print,  by  lying  in  the  water  for  a  short  time,  becomes  deve¬ 
loped.  It  is  finally  cleaned  off  by  gentle  agitation  in  cold  water. 

Under  and  Over-exposure. — It  is  of  course  very  desirable  that  the 
right  exposure  should  be  hit,  but  a  certain  latitude  of  error  can 
be  compensated  for  in  the  development.  If  the  print  clear  itself 
with  difficulty,  hotter  water  may  be  cautiously  applied,  not,  how¬ 
ever,  until  its  necessity  has  become  apparent. 

On  the  contrary,  under-exposure  will  show  itself  by  a  tendency 
to  clear  rapidly  as  soon  as  the  temperature  of  the  water  has  been 
a  little  raised  and  when  it  is  barely  tepid.  This  will  indicate  the 
necessity  of  keeping  down  the  temperature  and  finishing  the  print 
in  water  as  cool  as  will  clean  the  lights. 

The  print  thus  obtained  is  of  course  reversed.  In  some  cases 
this  is  a  matter  of  indifference,  but  more  frequently  it  is  neces¬ 
sary  that  the  print  should  correspond  with  the  object  itself,  as 
does  an  ordinary' silver  print.  This  correspondence  is  obtained 
in  either  of  two ’ways: — 

By  taking  Reversed  Negatives. — A  reversed  negative  bears  the 
same  relation  to. an  ordinary  one  as  an  image  in  the  looking-glass 
does  to  the  object-  itself.  Accordingly,  one  method  of  reversing 
negatives  is  to  have  a  small  mirror  placed  just  in  front  of  the 
lens,  making  an  angle  of  forty-five  degrees,  so  that  the  reflection 
in  the  mirror,  not  the  object  itself,  is  taken  on  the  film.  The 


CARBON  PRINTING. 


401 


mirror  must  have  only  one  reflecting  surface ;  must  be  silvered 
on  the  face  instead  of  the  back. 

Another  method  is  to  put  the  film  side  of  the  negative  away 
from  the  lens.  Two  precautions  are  here  necessary :  the  glass 
must  be  plate,  and  perfectly  free  from  scratches  and  faults ;  the 
ordinary  brass  spring  at  the  back  of  the  plate  must  be  removed, 
and  long  springs  of  silver  be  placed  at  the  ends,  so  that  tips  of 
the  springs  will  rest  upon  the  corners  of  the  plate. 

In  practice,  the  first  system  has  been  the  most  successful. 

By  Double  Transfer. — With  non-reversed  (ordinary)  negatives, 
if  the  final  print  is  required  to  be  non-reversed,  a  re-transfer 
must  be  made  on  paper  prepared  with  gelatine. 

Evidently  it  will  be  prudent  to  keep  down  the  temperature  in 
the  early  stages  of  the  operation,  and  to  raise  it  only  as  far  as 
becomes  manifestly  necessary. 

Re-transferring . — This  is  done  with  gelatine  solution. 

Water . 40  ounces. 

Glycerine . 1  ounce. 

Gelatine . 4  ounces. 

Heat  this  long  enough  to  expel  all  air-bubbles,  but  do  not  keep 
unnecessarily  long  in  fusion,  as  by  such  treatment  gelatine  loses 
to  some  extent  its  power  of  setting. 

Cover  the  surface  of  the  print  very  carefully  and  evenly  with 
solution,  either  by  floating  or  brushing,  then  hang  up  to  dry. 
Dampen  carefully  the  mount,  whether  this  be  paper  or  cardboard, 
avoiding  to  dampen  too  much,  lay  the  print  on  face  down,  and 
pass  at  once  through  the  rolling  press. 

The  print  is  now  left  for  a  day  to  dry  thoroughly  before  under¬ 
taking  the  last  operation,  that  of  removing  the  paper  which  has 
acted  as  a  support  during  development.  This  is  done  by  vigor¬ 
ously  rubbing  with  tufts  of  cotton  dipped  in  benzine.  Then 
raise  a  corner,  selecting  one  of  the  deep  shadows  where  the  film 
is  thick,  with  a  blunt  knife,  bend  it  well  back  and  peel  it  gently 
off.  In  mounting  on  paper,  Mr.  Swan  is  in  the  habit  of  subse¬ 
quently  laying  the  print  for  an  hour  in  a  five  per  cent,  solution 
of  alum,  a  step  which  the  writer  believes  he  .was  the  first  to 
suggest. 


402 


PHOTOGRAPHIC  MANIPULATION'S. 


§  3. — Other  Methods. 

Carbon  Direct  Printing. — In  the  case  of  objects  devoid  of  half¬ 
tone,  and  consisting  altogether  of  white  and  black,  the  transferring 
is  unnecessary.  If  gelatine  or  gum  be  mixed  up  with  solution 
of  bichromate  of  potash,  and  a  pigment  be  incorporated  with  it, 
this  mixture  may  be  spread  evenly  on  sized  paper,  and,  if  exposed 
under  a  negative,  a  positive  copy  is  obtained. 

The  writer  has  shown  elsewhere  that  gum  is  preferable  to  gela¬ 
tine  for  this  purpose,  inasmuch  as  it  may  be  spread  evenly  over 
the  paper  with  a  brush ;  gelatine  mixtures  cannot,  as  they  con¬ 
geal  in  the  operation.  He  also  showed  that  the  perfectly  pure 
whites  could  be  obtained  by  adding  albumen  to  the  mixture,  and 
not  without  it. 

Printing  through  the  Paper ,  -Laborde  first  suggested  this 

idea,  but,  in  spite  of  many  efforts,  it  has  never  been  practically 
successful,  the  grain  of  the  paper  interfering,  unless,  indeed,  Mr. 
Pouncy’s  prints  have  been,  as  stated,  so  obtained. 

Pounces  Process. — Excellent  prints  have  been  obtained  by  Mr. 
Pouncy,  an  early  and  unwearied  laborer  in  the  field  of  carbon 
printing.  In  this  process  the  sensitive  pigment  is  composed  of 
asphaltum,  printer’s  ink,  and  a  fatty  matter,  with  or  without  bi¬ 
chromate  of  potash.  The  matters  are  incorporated  with  the  aid 
of  heat,  and  strained.  All  the  information  given  by  Mr.  Pouncy 
is  that  there  must  be  more  ink  than  asphaltum,  that  it  should  be 
as  thick  as  cream,  and  give  an  opaque  coating  when  applied  to 
glass.  Only  some  sorts  of  asphaltum  give  good  results. 

The  sensitive  pigment  is  to  be  applied  to  paper  with  a  broad 
camel’s-hair  brush,  leaving  the  brush  in  the  pigment  when  not  in 
use.  The  paper  dries  in  a  few  minutes,  and  keeps  for  months. 

The  paper  to  be  used  should  be  a  very  transparent  tracing 
paper,  or  bank-post  rendered  transparent  with  poppy  oil.  Ex¬ 
pose  with  the  paper  side  next  to  the  negative,  and  develop  by 
immersion  in  turpentine. 

These  prints  are  advantageously  transferred  to  white  paper. 
After  the  print  has  become  thoroughly  hard  by  exposure  to  light 
and  air,  after  development,  varnish  the  surface  with  a  broad 
camel’s-hair  brush,  and  lay  the  picture  face  down  on  the  surface 
to  which  it  is  to  be  transferred,  and  press  in  a  copying  press ; 
when  dry,  moisten  the  transparent  paper,  and  it  will  come  off, 
leaving  the  print  behind. 


CARBON  PRINTING. 


403 


The  exposures  in  this  process  are  long;  from  three  to  five 
times  those  of  chloride  paper.  The  prints  are  very  beautiful, 
and  probably  have  the  highest  claim  to  permanence  of  any  pho¬ 
tographic  work  on  paper,  without  exception. 

Carbon  Printing  on  Glass. — The  writer  has  devised  an  extremely 
simple  mode  of  operating.  “  Tissue,”  as  sold,  is  placed  in  a  solu¬ 
tion  of  bichromate  of  potash,  one  ounce  to  twelve  of  water,  a 
clean  piece  of  plate  glass  is  slipped  under  it,  the  tissue  pressed 
close,  and  thus  contact  is  secured  without  bubbles.  After  drying, 
the  glass  face  is  cleaned,  the  negative  placed  against  it  (the  glass 
side),  and  the  printing  is  done  by  reflected  sunlight,  or  by  placing 
in  the  bottom  of  a  box  three  or  four  feet  long,  so  as  to  exclude 
diffused  light.  Develop  in  tepid  water.  No  transferring  is 
needed.  This  method,  when  well  managed,  gives  a  clean,  sharp 
image,  and  involves  but  very  little  trouble. 


PART  iy. 


THEORETICAL  CONSIDERATIONS. 


CHAPTER  I. 

GENERAL  OBSERVATIONS. 

When  we  attempt  to  study  the  functions  of  light,  we  find  our¬ 
selves  face  to  face  with  questions  which  continually  extend  and 
expand  as  we  consider  them,  until  we  are  lost  in  the  immensity 
of  the  subject. 

For  all  life,  such  as  we  know  it  on  this  planet,  has  been  ordained 
by  its  Creator  to  exist  only  under  the  influence  of  light.  By  that 
agency,  carbon  is  separated  from  the  carbonic  acid  of  the  atmo¬ 
sphere,  and  is  combined  into  all  those  organic  forms  of  nutriment 
upon  which  we  rely  to  support  life,  either  directly  as  food,  or 
indirectly  to  nourish  those  animals  which  are  eventually  to  con¬ 
stitute  our  food.  Thus,  everything  that  lives  upon  the  face  of 
our  planet  owes  its  existence  to  light. 

Light  is  so  powerful  in  its  influence  upon  organic  bodies  that 
there  exists  scarcely  one  which  is  not  directly  affected  by  it.  If 
an  organic  body  be  formed  by  the  affinities  of  its  component  parts 
acting  in  the  absence  of  light,  then  when  that  body  so  formed  is 
submitted  to  the  action  of  light,  the  affinities  of  its  elements  are 
in  a  vast  number  of  cases  so  altered  that  decomposition  results,  at 
least  if  moisture  be  present.  As  familiar  examples  may  be  men¬ 
tioned  that  almost  all  colors  are  bleached  by  exposure  to  sun¬ 
light,  almost  all  organic  substances  are  essentially  altered  in  their 
nature  by.  long  action  of  sunlight.  Perhaps  no  more  striking 
instances  can  be  adduced  than  those  of  the  whole  vegetable 
world.  Plants  of  every  description  undergo  incessant  changes 
under  the  action  of  light ;  these  changes  take  one  course  so  long 
as  the  plant  lives ;  with  its  death  a  new  order  of  changes  sets  in. 


GENERAL  OBSERVATIONS. 


405 


During  its  life  it  not  only  forms  cellular  and  woody  tissues  and 
chlorophyl,  &c.,  characteristic  of  vegetable  life  generally,  but 
also  vast  numbers  of  complex  organic  bodies,  such  as  the  vege¬ 
table  alkaloids,  the  gums,  the  resins,  the  sugars,  the  vegetable 
oils,  the  essential  oils,  &c.  &c.  After  the  death  of  the  plant,  an 
inverse  action  is  set  up,  and  these  substances  tend  to  resolve 
themselves,  under  the  influence  of  light,  heat,  and  moisture, 
more  or  less  completely  into  carbonic  acid  and  water. 

Inorganic  bodies  as  a  class  are  less  sensitive  to  light,  but  there 
are,  nevertheless,  very  many  even  of  these  in  which  a  change  of 
affinities  is  brought  about  by  its  agency. 

Most  commonly  the  action  of  light  is  a  reducing  one,  that  is, 
there  is  a  tendency  to  part  with  oxygen  (similarly  with  other 
chlorous  bodies,  as  iodine,  bromine,  and  chlorine).  This  is  analo¬ 
gical  with  the  action  of  light  in  producing  vegetation  by  which 
the  carbonic  acid  of  the  atmosphere  is  made  to  part  with  oxygen, 
and  enter  into  new  forms  of  combination.  So  that  the  regular 
and  normal  action  of  light  may  be  said  to  be  the  reducing  one. 

Occasionally,  however,  the  action  is  contrary,  and  a  combina¬ 
tion  with  the  oxygen  of  the  atmosphere  is  promoted.  Phosphorus 
is  an  example  of  this  exceptional  action,  its  union  with  oxygen 
is  accelerated  by  light.  Another  prominent  exception  may  be 
cited  in  the  action  of  light  upon  a  mixture  of  hydrogen  and 
chlorine,  bodies  which,  when  mixed  together,  show  no  tendency 
to  unite  in  the  dark,  but  do  so  with  explosion  when  light  is 
allowed  to  fall  upon  the  glass  vessel  in  which  these  gases  are 
mixed  in  proper  proportions. 

An  examination  into  the  action  of  light  in  those  processes 
which  the  photographer  employs,  shows  that  so  far  as  it  is  chemi¬ 
cal,  it  is  invariably  reducing.  Thus,  when  a  bichromate  is  ex¬ 
posed  to  light  in  the  presence  of  organic  matter,  the  agency  of 
the  light  enables  the  organic  matter  to  oxidize  itself  at  the  ex¬ 
pense  of  a  part  of  the  oxygen  of  the  chromic  acid.  When  a 
per-salt  of  iron  is  exposed  to  light,  it  tends  to  lose  one-third  of  its 
oxygen,  and  to  pass  to  the  condition  of  a  proto-salt.  The  same 
thing  takes  place  in  the  salts  of  uranium,  which  principle  forms 
the  basis  of  the  so-called  Wothlytype  process.  Some  other  metals 
are  acted  upon  similarly :  the  salts  of  mercury  tend  to  lose  half 
their  oxygen,  chloride  of  gold  may  lose  the  whole  of  its  chlorine, 
and  the  gold  may  be  revived  in  metallic  form. 


406 


PHOTOGRAPHIC  MANIPULATIONS. 


CHAPTER  II. 

ACTION  OF  LIGHT  ON  COMPOUNDS  OF  SILVER. 

§  1. — Chloride  of  Silver. 

Light  exerts  a  distinct  chemical  action  upon  chloride  of  silver, 
of  a  reducing  nature,  that  is,  the  chloride  passes  into  sub-chloride 
with  elimination  of  free  chlorine,  or  of  hypochlorous  acid.  If 
pure  precipitated  chloride  of  silver,  well  washed  and  freed  from 
all  organic  matter,  be  exposed  to  light  in  a  sealed  glass  tube,  it 
gradually  assumes  a  violet  color,  and  loses  chlorine.  In  the  dark 
it  regains  its  whiteness  by  recovering  the  chlorine  lost.  If  free 
nitrate  of  silver  be  present,  that  is,  if  the  chloride  of  silver  be 
moistened  by  solution  of  nitrate  of  silver,  the  coloration  proceeds 
much  more  rapidly. 

If  organic  matter  be  present,  the  decomposition  is  more  rapid 
still,  and  in  many  cases  the  sub-chloride  of  silver  appears  to  unite 
with  the  organic  matter,  giving  ris$  to  the  production  of  com¬ 
pounds  much  more  deeply  colored  than  the  simple  sub-chloride. 
Of  these  is  the  dark  chocolate-colored  substance,  passing  almost 
to  black,  which  constitutes  the  body  of  an  albumenized  paper 
print  before  toning. 

§  2.— Iodide  of  Silver. 

The  study  of  the  action  of  light  upon  iodide  of  silver  presents 
very  great  difficulties,  and  has  given  rise  to  considerable  differ¬ 
ence  of  opinion. 

In  studying  this  subject,  it  becomes  necessary,  as  the  writer  of 
this  manual  has  more  particularly  pointed  out  elsewhere,  to  con¬ 
sider  the  question  in  two  different  forms,  and  distinguish  between 
the  action  of  light  upon  iodide  of  silver  in  the  presence,  and  also 
in  the  absence  of  organic  or  other  bodies  capable  of  exerting 
special  influences  on  it. 

To  be  able  fully  to  eliminate  the  effect  of  these  latter,  the 
writer  devised  the  method  of  precipitating  metallic  silver  upon 


ACTION  OF  LIGHT  ON  COMPOUNDS  OF  SILVER.  407 


films  of  glass,  and  then  iodizing  these  films  with  iodine  dissolved 
in  solution  of  iodide  of  potassium.  It  had  been  held,  indeed,  that 
iodide  of  silver  formed  in  presence  of  excess  of  iodide  of  potas¬ 
sium  was  insensitive  to  light ;  this  view,  however,  the  writer  dis¬ 
proved  by  decisive  experiments,  and  it  is  now  abandoned. 

As  the  film  of  iodide  of  silver  upon  glass  was  very  liable  to 
slip  about,  an  expedient  was  found  to  fix  it,  but  substituting  ground 
glass,  and  this  method  of  experimenting  is  now  the  only  one 
known  that  is  capable  of  affording  reliable  results. 

By  these  experiments,  which  cannot  be  detailed  here,  the 
writer  was  enabled  to  show — 

1.  That  pure  iodide  of  silver  isolated  undergoes  no  chemical 
decomposition  even  by  very  prolonged  action  of  light.  Thus  a 
film  exposed  for  many  hours  to  brilliant  sunshine  was  placed 
aside  for  a  day  or  two  in  the  dark.  It  was  exposed  for  a  second 
or  two  under  a  negative,  and  the  image  of  that  negative  was  then 
developed  upon  it  without  difficulty. 

2.  But  if  an  organic  substance  be  present,  then  chemical  de¬ 
composition  does  take  place.  Thus,  if  a  film  of  iodide  of  silver 
upon  ground  glass  be  washed  over  with  a  solution  of  tannin,  and 
then  be  exposed  for  a  sufficient  time  under  a  negative,  a  visible 
image  of  the  negative  is  obtained. 

Development  on  Iodide  of  Ijilver. — Very  erroneous  notions  of  the 
nature  of  development  on  iodide  of  silver  have  often  been  enter¬ 
tained,  and  the  writer  himself  was  at  one  time  under  the  convic¬ 
tion  that  iodide  of  silver  might  undergo  such  a  physical  impression 
as  to  predispose  it  to  decomposition  when  brought  into  contact 
with  certain  substances.  Careful  and  extended  experiment  has 
led  him  to  return  to  his  older  opinion,  that  the  physical  impres¬ 
sion  of  light  upon  iodide  of  silver  is  such  as  merely  to  predis¬ 
pose  it  to  receive  a  falling  precipitate.  This'conception  should 
be  fully  mastered  by  the  student,  and  may  be  explained  as  fol¬ 
lows  : — 

If  we  take  a  saline  solution  which  is  just  ready  to  let  fall  a 
precipitate,  and  stir  it  well  in  a  glass  vessel,  allowing  the  end  of 
the  glass  rod  to  touch  the  sides  of  the  vessel  in  stirring,  we  shall 
find  that  (in  many  cases)  the  precipitate  will  form  first  and  in 
preference  on  all  those  parts  of  the  glass  which  have  been  touched 
by  the  rod.  Thus  it  may  be  said  that  the  previously  invisible 
path  of  the  rod  over  the  glass  has  been  developed  by  the  precipi¬ 
tate.  The  surface  of  the  glass  was  only  physically,  not  chemi- 


408 


PHOTOGRAPHIC  MANIPULATIONS. 


cally,  altered  by  the  passage  of  the  rod  over  it ;  and  yet  it 
attracted,  more  powerfully  than  the  rest,  the  descending  precipi¬ 
tate.  Just  so  the  part  of  the  iodide  film  which  has  been  touched 
by  light,  exerts  a  more  powerful  attraction  upon  the  descending 
precipitate  of  metallic  silver  from  the  developer  than  those  por¬ 
tions  which  have  not  been  touched. 

It  appeared  to  the  writer  that  although  the  similarity  of  these 
phenomena  was  sufficiently  obvious,  yet  the  two  might  be  brought 
closer  together  if  he  could  show  that  an  iodide  film  could  receive 
a  species  of  latent  image  by  mere  pressure,  independently  of  light, 
capable  of  being  developed  by  an  ordinary  developer.  Experi¬ 
ment  realized  this  without  difficulty.  Sensitive  collodion  films 
were  pressed  with  various  surfaces  having  raised  or  sunk  devices. 
Then  a  developer  poured  over  them  brought  out  these  devices 
with  great  distinctness,  the  silver  being  attracted  ahvays  in  prefer¬ 
ence  to  those  parts  which  had  received  the  pressure.  The  writer  does 
not,  however,  mean  to  affirm  that  the  action  of  light  is  necessarily 
mechanical,  as  in  the  foregoing  illustration  and  experiment. 

It  is  very  remarkable  that  although  invisible  images  may  be 
developed  on  both  chloride  and  bromide  of  silver,  yet  the  phe¬ 
nomena  are  of  quite  a  different  nature.  Development  on  pure 
iodide  of  silver  results  simply  from  |  power  in  the  film  to  attract 
to  itself  a  descending  precipitate,  and  is  independent  of  any  de¬ 
composition  of  the  iodide  in  the  film,  either  under  the  action  of 
light,  as  may  take  place  in  the  case  of  chloride  of  silver  and 
bromide  of  silver,  or  under  that  of  a  developer,  as  may  happen  in 
the  case  of  bromide,  of  silver. 

That  the  development  in  the  case  of  iodide  of  silver  is  perfectly 
independent  of  any  decomposition  of  the  iodide  film,  is  shown  by 
experiments  published  by  the  writer,  together  with  Dr.  Shepard, 
of  Providence,  in  which,  after  an  image  had  been  developed  on  an 
iodide  film,  it  was  dissolved  away  with  solution  of  acid  pernitrate 
of  mercury,  and  was  then,  after  washing,  reproduced  by  a  second 
application  of  a  developer.  This  exhibits  in  a  striking  light  what 
the  writer  holds  to  be  the  peculiar  and  characteristic  action  of 
iodide  of  silver,  viz.,  that  it  is  so  modified  by  the  action  of  light 
as  to  be  capable  of  forming  an  image  out  of  the  silver  in  the 
developer,  without  itself  having  undergone  decomposition  either 
during  exposure  or  under  development.  In  this  way  only  does 
it  seem  possible  to  explain  the  fact  that  a  developed  image  may 


ACTION  OF  LIGHT  ON  COMPOUNDS  OF  SILVER.  409 

be  dissolved  away,  and  the  power  nevertheless  be  left  in  the  film 
to  reproduce  the  image  by  a  second  development. 

It  has  been  already  explained  that  in  the  presence  of  certain 
organic  and  other  bodies,  iodide  of  silver  undergoes  chemical 
decomposition,  and  the  same  seems  to  be  true  when  nitrate  of 
silver  is  present.  When,  therefore,  instead  of  experimenting 
upon  a  film  of  iodide  of  silver,  isolated  on  glass,  we  take  a  com¬ 
mon  sensitized  plate  in  which  both  nitrate  of  silver  and  an 
organic  body  (collodion)  are  present,  the  conditions  are  essen¬ 
tially  changed,  and  chemical  decomposition  undoubtedly  takes 
place.  Consequently,  in  the  ordinary  wet  collodion  process, 
there  appear  to  be  two  invisible  images  simultaneously  present 
in  the  film — one  a  latent  physical  image  due  to  the  action  of 
light  upon  the  iodide,  the  other  a  chemical  image,  invisible 
simply  by  reason  of  its  tenuity.  Both  of  these  may  serve  as 
bases  of  development. 

For  want  of  distinguishing  clearly  between  these  conditions, 
and  of  remembering  that  what  takes  place  in  the  case  of  iodide 
of  silver  isolated  from  all  other  bodies  is  very  different  from 
Avhat  takes  place  when  free  nitrate  of  silver  or  certain  organic 
bodies  are  present — for  want  of  bearing  this  steadily  in  mind, 
much  that  has  been  written  on  the  subject  of  this  latent  image 
has  little  or  no  real  value.  * 

The  above  are  the  views  which  the  writer  has  entertained  and 
endeavored  to  prove.  In  the  opinion  of  some  photo-chemists, 
however,  the  action  of  light  upon  iodide  of  silver  is  always 
chemical,  and  no  impression  is  formed  except  by  actual  decom¬ 
position.  But  this  opinion  seems  to  be  at  variance  with  observed 
facts,  and  the  reactions  of  iodide  of  silver  cannot  be  satisfactorily 
explained  by  it. 

It  will  be  interesting  to  note  that  in  the  case  of  iodide  of  silver 
the  chemical  latent  image  always  offers  a  stronger  basis  of  develop¬ 
ment  than  the  physical.  Now  it  has  been  already  explained  that, 
according  to  the  view  entertained  by  the  writer,  the  chemical 
image  is  never  produced  upon  isolated  iodide  of  silver,  but  only 
when  some  suitable  body  is  present  to  give  rise  to  its  production, 
consequently  it  follows  that  the  presence  of  that  body  capable  of 
giving  rise  to  the  production  of  a  chemical  image,  may  greatly 
exalt  the  sensibility  of  the  iodide.  It  is  for  this  reason  that  the 
presence  of  the  bath  solution  (containing  free  nitrate  of  silver) 
in  wet  plates,  and  certain  bodies,  such  as  tannin,  gum,  gallic  acid, 
27 


410 


PHOTOGRAPHIC  MANIPULATIONS. 


etc.,  in  dry  plates,  greatly  diminishes  the  exposure  needed.  These 
latter  substances  have  been  called  preservatives,  though  it  is  evi¬ 
dent  that  they  are  sensitizers  precisely  as  nitrate  of  silver  is  a 
sensitizer. 

As  the  production  of  a  “  chemical  image,”  i.  e.,  one  depending 
upon  the  actual  decomposition  of  the  iodide,  must  always  arise 
from  a  separation  of  iodine  to  a  greater  or  less  extent  from  the 
silver  present,  so  it  seemed  natural  to  suppose  that  the  greater  sen¬ 
sitiveness,  or,  in  other  words,  greater  proneness  to  decomposition 
resulting  from  the  presence  of  so-called  preservatives,  had  its 
origin  in  an  affinity  of  the  preservative  for  iodine,  which  affinity, 
insufficient  in  itself  to  produce  decomposition,  would  neverthe¬ 
less  aid  the  action  of  the  light.  This  explanation  was  first  made 
by  Poitevin,  and  has  received  general  acceptance.  Yogel  has 
affirmed  that  all  preservatives  have  this  characteristic,  that  they 
show  their  affinity  for  iodine  by  decolorizing  the  blue  solution 
of  iodide  of  starch. 

But  few  experiments  appear  to  have  been  made  to  test  this 
view.  The  writer,  at  a  time  when  he  was  experimenting  with 
many  new  preservatives,  tested  many  of  those  which  had  shown 
themselves  useful,  with  the  iodide  of  starch,  found  that  they  all 
decolorized  it.  What  tends,  however,  somewhat  to  weaken  this 
argument,  is  that  the  most  powerful  sensitizers  were  not  always 
those  that  most  rapidly  decolorized  the  blue  test.  Thus  tincture 
of  stramonium  showed  itself  to  be  a  most  powerful  sensitizer, 
but  exhibited  so  little  action  upon  the  blue  solution,  that  twenty- 
four  hours  were  necessary  to  render  the  action  visible. 

§  3.— Bromide  of  Silver. 

The  action  of  light  upon  bromide  of  silver  has  been  less  studied 
than  that  of  iodide,  because  the  difficulties  which  it  presents  have 
been  less  evident  than  those  in  the  case  of  the  iodide.  For  it  was 
easily  shown  in  the  case  of  bromide  of  silver  that  a  chemical 
decomposition  does;  take  -place  by  continued  action  of  light.1 
Hence  it  was  supposed  that  no  physical  action  of  light  took  place, 
inasmuch  as  none  was  apparently  needed  to  explain  the  pheno¬ 
mena  observed. 

1  This  fact  the  writer  has  carefully  verified  upon  films  of  bromide  of  silver 
isolated  upon  surfaces  of  ground  glass. 


ACTION  OF  LIGHT  ON  COMPOUNDS  OF  SILVER.  411 


But  the  writer  has  pointed  out  elsewhere  that  the  mere  fact  of 
the  possibility  of  development  by  pyrogallic  acid  in  the  absence  of  any 
free  soluble  silver  compound ,  is  in  itself  an  unanswerable  argument 
for  the  existence  of  such  a  physical  image. 

Upon  a  dry  collodio-bromide  plate  perfectly  washed  and  hav¬ 
ing  present  no  trace  of  the  nitrate  of  silver,  the  application  of 
pyrogallic  acid  will  develop  a  visible  image.  Whence  does  this 
come  ?  The  image  is  evidently  a  sub-bromide  of  silver,  perhaps 
combined  with  organic  matter,  but  that  the  bromide  of  silver  in 
the  film  afforded  the  sub-bromide  by  decomposition  is  sufficiently 
clear. 

Now  although  this  image  may  be  developed  where  there  Avas 
no  image  visible  upon  the  plate  after  its  exposure,  let  us  even 
suppose  for  argument  that  there  was  a  faint  visible  image.  If 
the  development  were  conducted  with  nitrate  of  silver  present, 
this  faint  visible  image  might  certainly  act  as  a  foundation  upon 
which  the  strong  image  was  built  up.  But  nothing  of  the  sort 
can  take  place  where  the  alkaline  development  is  conducted  in 
the  absence  of  all  silver  compounds  except  those  in  the  plate. 

It,  therefore,  appears  clear  that  a  latent  physical  image  may 
exist  on  bromide  as  well  as  on  iodide  of  silver. 

But  the  difference  between  these  compounds  in  respect  of  the 
action  of  light  upon  them  is  very  striking. 

On  iodide  of  silver  the  latent  physical  image  is  produced  where 
the  iodide  is  isolated. 

But  on  bromide  only  where  a  “sensitizer”  is  present. 

On  bromide  isolated,  the  action  of  the  light  can  only  produce 
a  chemical  image ;  on  iodide  isolated,  it  can  produce  a  physical 
image  only. 

The  action  of  the  light  upon  bromide  of  silver,  isolated,  must 
be  enormously  long  to  produce  an  impression  capable  of  being 
developed;  the  sensitizer  abridges  this 'period  vastly  more  than 
in  the  case  of  iodide. 

But  on  bromide  isolated,  the  long-continued  action  of  light 
may  produce  a  strong,  visible  image  (in  faii  experiment  by  the 
writer  this  was  attained  by  four  hours’  exposure  to  strong  sun 
under  a  negative),  which  cannot  take  place  in  the  case  of  iodide. 

Development  on  Bromide  of  Silver.— In  the  case  of  iodide  of 
silver,  we  have  seen  that  development  is  essentially  the  attraction 
to  the  film  of  a  descending  precipitate,  the  film  itself  remaining 
(chemically)  unaltered.  But  in  the  case  of  bromide  of  silver 


412 


PHOTOGRAPHIC  MANIPULATIONS 

(acted  on  by  light  in  the  presence  of  tannin,  or  other  sensitizer) 
the  alkaline  development  consists  essentially  in  a  reduction  of  the 
bromide  in  the  film,  and  the  production  thereby  of  a  more  or  less 
complex,  deeply-colored  substance,  forming  the  image. 

The  remarkable  distinctions  between  these  two  developments, 
as  respects  their  essential  characters,  correspond  to  equally  great 
differences  in  the  practical  operations  based  upon  them.  So  that 
in  the  wet  processes,  in  which  iodide  of  silver  is  the  altogether 
essential  body,  we  see  those  forms  succeed  best  in  which  a  de¬ 
scending  precipitate  is  applied  to  the  invisible  image. 

But  in  the  dry  bromide  processes  we  find  only  one  thing  essen¬ 
tial  :  that  to  the  exposed  plate  there  shall  be  presented  a  substance 
like  pyrogallic  acid,  which  has  a  natural  tendency  to  provoke 
reduction.  This  substance  at  once  starts  a  decomposition  in  those 
parts  that  have  been  exposed  to  light.  We  may  enhance  its 
decomposing  action  by  alkalies,  and  so  exalt  that  decomposing 
agency  until  it  is  alone  sufficient  to  produce  such  an  image  as  we 
want ;  or,  we  take  the  image  so  produced,  and  by  adding  silver 
and  acetic  acid,  we  may  build  upon  it  a  denser  image  for  our  pur¬ 
pose.  So  far  as  this  building  up  is  concerned,  we  proceed  upon 
the  same  principles  as  in  the  wet  process,  but  this  second  step 
does  not  in  the  least  affect  the  character  of  the  first,  and  that  first 
step  differs  absolutely  and  essentially  from  anything  that  belongs 
to  the  wet  development. 

It  is  then  (and  this  is  what,  if  the  writer  is  not  mistaken,  has 
not  before  been  correctly  presented)  by  a  careful  consideration  of 
the  essential  characters  of  these  two  developments,  that  we  arrive 
at  the  essential  differences  between  the  invisible  image  as  formed 
on  iodide,  and  on  bromide  of  silver.  Each  in  its  absolute  essence 
and  freed  from  such  accidental  phenomena  as  may  accompany  it 
(and  may  lead  to  the  production  of  a  chemical  image),  is  physical 
and  not  chemical  in  its  nature.  But  in  the  iodide  the  physical 
impression  is  one  tending  to  cause  the  attraction  of  a  descending 
precipitate,  in  th-e  bromide  it  is  one  predisposing  to  decomposition 
when  a  reducing  agent  of  a  proper  character  is  presented. 


ACTION  OF  PORTIONS  OF  THE  SPECTRUM.  413 


CHAPTER  III. 

ACTION  OF  VARIOUS  PORTIONS  OF  THE  SPECTRUM. 

When,  instead  of  exposing  sensitive  bodies  to  ordinary  light, 
we  let  fall  upon  them  a  solar  spectrum,  we  find  that  its  different 
portions  exercise  widely  different  influences. 

We  find,  also,  that  the  nature  of  the  'prism  used  singularly 
affects  the  influences  exerted  by  the  different  portions  into  which 
it  separates  white  light.  Thus,  for  example,  with  a  flint  glass 
prism,  the  most  powerful  actinic  force  is  exerted  by  the  invisible 
rays  just  beyond  the  violet.  But  if  a  prism  filled  with  sulphide 
of  carbon  be  used,  a  spectrum  is  formed,  devoid,  or  nearly  so,  of 
invisible  ultra  violet  rays,  capable  of  acting  upon  sensitive  paper. 
A  series  of  very  interesting  experiments,  chiefly  made  by  Her- 
schel,  on  the  action  of  different  portions  of  the  spectrum,  have 
been  tabulated,  and  will  be  found  in  Hunt’s  valuable  Researches 
on  Light. 

As  respects  the  silver  haloids,  the  action  of  light  commences 
far  beyond  the  visible  rays,  and  extends  some  distance  into  the 
visible  spectrum.  Bromide  of  silver  is  very  faintly  affected  by 
green  rays,  which  do  not  act  upon  iodide.  It  has,  therefore,  a 
slightly  wider  range  of  sensitiveness  than  iodide. 

Below  the  green  come  those  brighter  rays  which  form  the 
principal  illuminating  part  of  white  light.  These  are  without 
effect  upon  sensitive  films  of  the  silver  haloids  that  have  never 
been  exposed  to  light.  But  Ed.  Becquerel  has  shown  that  these 
less  refrangible  rays  have  a  “continuing”  power,  that  is,  that 
although  incapable  of  themselves  to  commence  an  impression  upon 
a  sensitive  surface,  even  by  a  very  prolonged  action,  yet  if  that 
action  be  set  up  by  the  more  refrangible  rays;  these  less  re¬ 
frangible  ones  can  continue  and  increase  It.  Thus,  if  paper  pre¬ 
pared  with  iodide  of  silver  be  exposed  to  the  spectrum,  the  im¬ 
pression  ends  with  the  blue  rays.  But  if  it  be  but  exposed  for 
a  second  or  two  to  light,  and  then  to  the  spectrum,  and  if  a  de¬ 
veloper  be  applied,  an  impression  is  found  to  have  been  made 
extending  to  the  very  end  of  the  visible  spectrum. 


414 


PHOTOGRAPHIC  MANIPULATIONS. 


What  is  also  remarkable  in  this  very  interesting  investigation 
is,  that  the  bodies  which  act  as  a  support  to  the  silver  compound 
may  exercise  an  important  influence  on  the  effects  produced. 
Thus  the  iodide  and  chloride  of  silver  in  collodion  or  paper,  or 
on  a  metallic  film,  are  subject  to  this  “  continuing”  power. 
Bromide  of  silver,  when  formed  on  a  daguerreotype  plate,  is  not; 
formed  on  collodion  or  on  paper,  it  is.  The  image  of  the  spectrum, 
when  formed  on  bromide  of  silver  on  a  plate ,  is  much  longer 
than  the  image  upon  chloride  or  iodide  also  on  a  plate,  whereas 
bromide  in  collodion  or  on  paper  gives  a  spectrum  no  longer 
than  iodide  or  chloride.1 

These  results  are  as  important  in  their  relations  to  photo¬ 
graphy  as  they  are  interesting  in  themselves,  and  their  bearing 
on  the  negative  process  is  too  evident  to  need  that  the  writer 
should  dwell  on  it.  Only  it  may  be  remarked  that  they  explain 
in  part  some  of  Mr.  Rutherfurd’s  results  in  photographing  spectra 
on  collodion ;  they  seem,  however,  to  indicate  that  in  his  ex¬ 
periments  the  spectrum  was  not  wholly  purified  from  wfliite  light, 
for  in  these  experiments  impressions  of  many  of  the  less  refran¬ 
gible  portions  of  the  spectrum  were  obtained  in  collodions  con¬ 
taining  the  silver  haloids. 

Heliochromy. 

It  has  been  long  known  that  the  various  colors  of  the  spectrum 
had  the  power  of  impressing  themselves  upon  certain  sensitive 
surfaces,  especially  upon  sub-chloride  of  silver.  So  that  if  a  piece 
of  paper  be  impregnated  with  chloride  of  silver  and  then  be  ex¬ 
posed  to  light  till  it  darkens  somewhat,  it  may  in  this  condition 
be  exposed  to  daylight  under  colored  glasses,  and  after  a  certain 
amount  of  exposure,  will  be  found  to  assume  the  color  of  the 
glass  under  which  it  was  exposed.  Becquerel  has  varied  the  ex¬ 
periment  by  using  metallic  plates ,  on  which  a  coating  of  chloride 
of  silver  was  formed.  Poitevin  discovered  that  bichromate  of 
potash  aided  chloride  paper  in  reproducing  natural  colors. 

But  neither  have  the  results  so  far  obtained  been  at  all  beauti¬ 
ful,  nor  has  it  been  found  possible  to  render  them  permanent. 
At  the  same  time,  the  experiments  above  referred  to  are  curious 
and  interesting,  and  there  is  no  doubt  that  it  is  in  the  power  of 
photography  to  reproduce  all  the  colors  of  nature. 


1  Becquerel,  La  Lumiere,  II.  pp.  89-92. 


PAET  V. 


CHAPTER  I. 

PHOTOGRAPHY  IN  ITS  RELATIONS  TO  HEALTH. 

§  1. — Poisons. 

In  adopting  a  pursuit,  whether  simply  with  a  view  to  interest 
and  amusement,  or  with  the  design  of  serious  study  and  investi¬ 
gation,  or  as  a  business  enterprise,  every  one  should  attentively 
consider  its  relations  to  his  health.  Permanent  injury  to  bodily 
health  is  an  evil  so  serious  that  its  full  magnitude  is  appreciated 
by  none  who  have  not  learned  by  their  own  bitter  experience. 
The  writer,  therefore,  appeals  to  the  good  sense  of  every  one 
who  may  adopt  this  manual  as  his  guide  through  the  study  of 
photography,  in  the  first  place  to  neglect  none  of  the  general 
precautions  which  will  be  here  recommended  ;  and  in  the  second, 
should  he  find  his  health  in  any  way  suffer,  to  ascertain  at  once 
to  what  that  injury  is  ascribable,  and  to  lose  no  time  in  taking 
such  special  action  as  the  case  may  need.  Speaking  from  per¬ 
sonal  experience,  and  having  witnessed  evil  results  in  others,  the 
writer  earnestly  desires  to  induce  the  habitual  adoption  of  effec¬ 
tive  precautions. 

It  is  not  that  photography  is  necessarily  a  hurtful  art,  but  its 
practice  brings  its  votaries  into  contact  with  several  very  strong- 
poisons,  which,  if  used  without  great  care,  and  still  more,  if  used 
with  the  heedlessness  that  is  only  too  common,  are  liable  to  pro¬ 
duce  the  very  worst  effects.  These  substances  are  principally 
ether ,  collodion ,  cyanide  of  potassium,,  corrosive  sublimate ,  chloride  of 
gold,  nitric  acid ,  acetic  acid ,  and  ammonia. 

Ether ,  whether  swallowed  or  inhaled  as  vapor,  has  a  remark¬ 
able  effect,  which,  like  that  of  many  other  active  agents,  is 
twofold,  stimulating  and  sedative.  The  first  tendency  is  to  pro- 


416  PHOTOGRAPHY  IN  ITS  RELATIONS  TO  HEALTH. 

duce  a  species  of  imperfect  intoxication,  soon  followed  by  more 
or  less  prostration ;  this  sedative  effect  has  led  to  its  being  used 
in  medicine  under  the  name  of  11  Hoffmann’s  Anodyne.”  The 
effect  of  its  continued  use  is  to  produce  languor,  depression  of 
spirits,  and  bodily  prostration. 

Collodion ,  from  the  large  quantity  of  ether  which  it  contains, 
produces  the  specific  effects  characteristic  of  that  substance,  but 
also  other  effects,  the  precise  source  of  which  is  not  well  under¬ 
stood.  When  collodion  becomes  much  ripened,  and  especially 
when  it  takes  on  a  deep  color,  it  is  found  to  give  off  a  very  irri¬ 
tating  vapor,  which  attacks  the  face,  and  especially  the  eyelids, 
producing  severe  inflammation.  Cases  have  been  cited  in  which 
photographers  have  been  in  this  way  obliged  to  interrupt  their 
pursuit  for  times  varying  from  a  few  days  to  many  months. 
When  the  photographer  perceives  a  disposition  to  irritation  and 
inflammation  in  the  face,  he  may  at  once  suspect  his  collodion  of 
being  the  cause. 

Cyanide  of  potassium  is,  of  course,  the  most  dangerous  chemical 
with  which  the  photographer  comes  into  contact.  For  clearing 
both  positives  and  negatives,  especially  the  former,  it  keeps  its 
hold  upon  photographers,  particularly  amongst  careless  manipu¬ 
lators,  through  two  causes.  First,  if  by  mismanagement  the  nega¬ 
tive  is  a  little  fogged,  cyanide,  which  has  a  stronger  solvent  action 
than  hyposulphite,  tends  to  clear  it  up.  Second,  the  transfer  of 
small  portions  of  cyanide  to  other  solutions  by  dirty  fingers,  has 
not  the  absolutely  disastrous  results  that  follow  such  transfers  of 
hyposulphite.  These  considerations  are  not  in  the  least  credit¬ 
able  to  the  photographer  who  is  influenced  by  them. 

Cyanide  of  potassium  is  a  compound  of  prussic  acid  with 
potash.  In  this  compound  it  retains  all  the  dangerous  proper¬ 
ties  that  characterize  it'  in  the  free  state.  In  fact,  a  solution  of 
cyanide  slowly  but  continually  decomposes,  absorbing  carbonic 
acid  from  the  air  and  giving  off  prussic  acid  in  the  form  of  gas. 

This  poison  may  act  in  three  ways.  Leaning  over  a  bath  of  it, 
or  even  remaining  in  a  room  containing  a  solution  of  it  exposed 
on  a  considerable  surface  to  the  air,  a  small  quantity  of  prussic 
acid  is  continually  inhaled. 

In  manipulating  with  its  solutions,  the  hands  come  into  contact 
with  it.  How  far  chemical  solutions  are  taken  up  by  a  perfectly 
sound  skin  has  been  a  matter  of  considerable  discussion  among 
physicians,  but  recent  careful  experiments  made  in  Paris  leave 


POISON'S. 


417 


no  doubt  that  the  skin  continually  absorbs  liquids  which  remain 
in  contact  with  it. 

If,  however,  the  continuity  of  the  skin  be  broken  by  a  scratch, 
cut,  pimple,  or  otherwise,  cyanide  is  readily  absorbed  at  such 
places,  and  a  considerable  amount  of  local  inflammation  may  be 
produced.  In  some  cases  paralysis  of  the  limbs  has  been  affirmed 
to  have  resulted,  and  even  paralysis  of  the  whole  side. 

For  several  years  past  the  photographic  journals  have  pub¬ 
lished  numbers  of  letters  from  photographers  who  have  had 
their  health  injured,  or,  in  many  cases,  ruined  by  the  action  of 
their  chemicals,  and  especially  by  cyanide.  Paralysis  is  the  most 
common  result,  attacking  most  frequently  an  arm,  but  sometimes 
the  entire  side.  One  describes  his  hands  as  for  months  continu¬ 
ally  exuding  some  anomalous  secretion,  sticking  them  fast  to  his 
gloves,  and  interfering  with  their  use.  Another  complains  of 
intense  pains  in  the  fingers,  only  to  be  rendered  endurable  by 
keeping  them  for  hours  in  cold  water.  Others  find  the  whole 
bodily  health  broken  down,  and  no  help  to  be  obtained  from 
medicine.  One  photographer  (M.  Davanne),  after  having  had  his 
hands  wet  with  cyanide  solution,  moistened  them  with  acetic 
acid,  and  was  almost  instantly  struck  down  insensible  with  symp¬ 
toms  of  violent  poisoning.  His  friends  barely  saved  him  by  long- 
continued  pouring  of  cold  water  on  the  head. 

It  should  always  be  remembered  that  when  any  substance  or 
compound  having  an  acid  reaction  comes  into  contact  with  cyan¬ 
ide  of  potassium,  the  dangerous  tendencies  of  the  latter  are  greatly 
increased — in  fact,  prussic  acid  is  at  once  set  free. 

A  very  painful  class  of  casualties  are  those  resulting  from  care¬ 
lessness  with  cyanide.  Solutions  are  left  about ;  sometimes  the 
incredible  carelessness  of  leaving  them  in  drinking  tumblers  is 
committed.  For  all  lives  lost  in  this  way  (and  there  have  been 
many),  he  who  left  the  solution  about  is  morally  responsible. 
Once  for  all,  the  use  of  this  chemical  should  be  abandoned  totally 
by  photographers.  If  any  insist  on  using  it,  the  least  such  can 
do  is  to  keep  it  exclusively  in  vessels  marked  conspicuously, 

POISON. 

Corrosive  sublimate  is  another  dangerous  chemical,  but  not 
capable  of  acting  by  inspiration  through  the  lungs.  Accidents 
with  sublimate  arise  either  from  absorption  or  internal  adminis¬ 
tration. 

Absorption  through  the  skin  takes  place  slowly,  and  the  fingers 


418  PHOTOGRAPHY  IN  ITS  RELATIONS  TO  HEALTH. 

may  be  occasionally  wetted  with  sublimate 'solution  without  any 
noticeable  bad  results  ;  the  danger  lies  in  this,  that  there  is  no  safe 
line  that  can  be  drawn,  and  that  the  photographer  can  form  no 
conception  as  to  the  point  to  which  he  may  go  with  impunity. 
Evil  must  be  done  before  its  danger  can  be  recognized. 

Administered  internally,  sublimate  is  a  powerful  corrosive 
poison. 

Chloride  of  gold  acts  as  a  poison  by  causing  deep  and  severe 
ulcerations  upon  the  fingers  of  those  who  are  continually  working 
in  toning  baths.  Such  manipulation  should  be  managed  by  means 
of  spatulas  and  forceps  of  glass  or  whalebone. 

Nitric  acid  acts  toxically  through  the  lungs.  It  stains  the  skin 
a  deep  yellow,  which  lasts  until  the  epidermis  is  worn  off,  but  no 
other  evil  seems  to  result  from  contact.  It  is  possible  that  it  is 
not  absorbed,  but  that  it  kills  the  skin  too  quickly  for  such  an 
effect.  Nitric  acid  diffused  through  the  atmosphere  and  inhaled, 
acts  as  a  direct  poison.  Some  years  since,  Mr.  Stevens,  together 
with  an  assistant,  undertook  to  sop  up  a  quantity  of  nitric  acid 
spilt  by  the  breaking  of  a  large  vessel,  an  act  which  resulted 
fatally  to  the  one  and  nearly  so  to  the  other. 

In  less  quantities,  and  inhaled  over  a  longer  time,  it  may  pro¬ 
duce  irritation  of  the  lungs  and  chest  diseases. 

Acetic  acid  acts  similarly  to  nitric,  but  in  a  less  degree.  Its 
fumes  are  very  irritating  to  the  lungs,  especially  to  weak  ones. 
The  quantity  of  acetic  acid  used  in  photographic  operations  is 
often  very  large,  so  that  in  many  professional  establishments 
there  is  always  a  strong  smell  of  this  acid.  Such  a  state  of  affairs 
must  be  hurtful  to  every  one  connected  with  the  place,  and  ought 
to  be  done  away  with  at  any  cost. 

Pyrogallic  acid  has  been  stated  lately  to  be  an  active  poison, 
having,  in  its  action  on  the  system,  certain  analogies  with  phos¬ 
phorus. 


§  2. — Remedies. 

General. — It  is  evident  that  all  poisons  which  are  liable  to  be 
carried  upon  the  atmosphere  should,  as  far  as  possible,  be  kept  in 
closed  vessels.  Cyanide  should  never  be  left  in  open  pans  or 
baths.  Nitric  acid  baths  used  for  cleaning  (for  which  purpose 
bichromate  and  sulphuric  acid  is  far  preferable ;  see  article  on 
cleaning  plates)  should  never  be  left  exposed  to  the  atmosphere, 


KEMEDIES. 


419 


but  the  pans  or  baths  should  be  protected,  and  be  kept  under  a 
chimney  or  a  draught  of  some  sort. 

Next  to  avoiding  the  production  of  fumes,  the  best  thing  is 
ventilation.  In  the  case  of  ether  and  collodion,  this  is  the  only 
efficient  means,  as  the  fumes  of  collodion  cannot  be  kept  out  of 
the  air.  For  this  reason  plates  should  be  collodionizefl,  not  in  the 
open  air  of  the  dark  room,  but  in  a  sort  of  closet  partitioned  off 
and  provided  with  a  vent  above  and  below.  The  operator  is 
outside  of  such  a  closet,  and  the  fumes  are  not  inhaled  as  the 
plate  is  coated.  This  is  a  very  important  precaution. 

When  acid  fumes  have  got  into  the  air,  their  removal  can  often 
be  expedited  by  pouring  out  ammonia.  This,  though  efficient, 
has  the  disadvantage  of  causing  thick  white  clouds,  which  sub¬ 
side  by  degrees  only.  Still,  its  use  is  occasionally  valuable. 

Special. — Poisons  taken  internally  must  be  treated  with  specific 
remedies ;  the  object  is  always  to  bring  the  poisonous  matter  into 
some  inert  compound. 

Cyanide  of  potassium  has  the  remarkable  property  of  taking 
up  iron  and  forming  a  perfectly  innocuous  substance  known  as 
yellow  prussiate  of  potash,  ferrocyanide  of  potassium.  Proto- 
sulphate  of  iron  may,  therefore,  be  taken  internally  in  consider¬ 
able  quantity.  Cyanide  of  potassium,  in  presence  of  a  mixture 
of  a  protosalt  and  persalt  of  iron,  is  converted  instantly  into 
Prussian  blue,  a  substance  not  at  all  injurious  to  the  system. 
Those  who  use  cyanide  habitually,  will  do  well  to  keep  the  mix¬ 
ture  of  proto  and  persulphate  of  iron  in  readiness  for  accidents  to 
others,  if  not  to  themselves.  Common  sulphate  of  iron  in  solu¬ 
tion,  by  continued  exposure  to  air,  peroxidizes,  and  may  be  used 
for  this  purpose. 

For  corrosive  sublimate  when  taken  internally,  white  of  egg  is 
usually  administered.  The  quantity  of  the  remedy  must  be  con¬ 
siderable — the  raw  white  of  one  egg  to  each  three  or  four  grains 
of  the  poison  swallowed. 

Poiso?is  in  cuts  and  scratches  should  be  immediately  treated  with 
the  same  remedies  as  those  advised  where  the  poison  has  been 
taken  into  the  stomach.  For  injuries  occasioned  by  the  continuous 
absorption  of  poisons,  no  satisfactory  remedies  can  be  recom¬ 
mended,  recourse  must  be  had  to  the  advice  of  an  educated  and 
intelligent  physician. 

The  writer  feels  that  he  cannot  leave  this  subject  without  again 
advising  photographers  to  pay  more  attention  to  the  conditions 


420 


CHEMICAL  MANIPULATIONS. 


of  health  than  is  generally  done.  Those  who  have  the  direction 
and  management  of  establishments,  should  never  forget  that 
those  whom  they  employ  are  often  much  more  exposed  to  these 
dangers  than  themselves,  without  having  the  opportunity  or  the 
privilege  of  introducing  better  arrangements  and  precautions. 
And  that,  However  employers  may  feel  disposed  to  risk  their  own 
health,  they  are  not  justified  in  causing  others,  either  ignorantly 
or  knowingly,  to  share  such  dangers.  Many  a  man,  when  he  has 
found  his  nervous  system  permanently  injured,  or  his  lungs 
weakened,  commences  care-taking  when  it  is  too  late.  The  need¬ 
ful  precautions  are  neither  many  nor  troublesome ;  they  should 
be  taken  from  the  outset,  and  steadily  persevered  in. 


CHAPTER  II. 

CHEMICAL  MANIPULATIONS. 

Some  of  the  simpler  chemical  manipulations  are  frequently 
needed  in  photography,  and  deserve  a  brief  description  here. 

§  1. — Weighing  and  Measuring. 

No  operations  are  commoner  or  seem  easier  than  these,  and  yet 
in  none  are  mistakes  more  frequent. 

Weighing.— d?or  the  operations  of  photography,  a  small  bal¬ 
ance  like  that  on  page  421,  having  a  nine  or  ten  inch  beam,  will 
be  the  most  suitable,  using  a  heavier  and  commoner  pair  of  scales 
for  weights  over  one  or  two  ounces.  Fig.  142  represents  the 
French  pattern  of  “  trebuchet ”  or  tilting  scale,  now  largely  manu¬ 
factured  here.  The  panA  rest  on  the  box  until  the  lever  is 
pressed,  when  they  swing  loose. 

In  weighing,  it  is -necessary  always  to  beware  of  “sticking.” 
When  the  pans  are  nearly  equally  loaded,  but  not  exactly^  the 
needle  may  point  at  the  centre  by  reason  of  the  beam  not  moving 
with  ^entire  freedom.  By  making  the  pans  oscillate  a  little,  it 
will  bb  easy  to  see  if  the  needle  moves  on  each  side  to  the  same 
distance  from  the  centre. 


WEIGHING  AND  MEASURING. 


421 


Fig.  142. 


Inattention  to  reckoning  the  weights  is  another  common  source 
of  mistakes,  especially  with  our  defective  system. 

The  following  are  the  details  of  the  weights  as  now  used.  The 
grain  is  the  same  always. 

Avoirdupois. 

1  drachm  =-64r4  grains  nearly. 

1  ounce  =  437£  grains.  ■=•  /  t>  drachm  5 
1  pound  =  16  ounces  =  7000  grains. 


Apothecaries. 

1  draclim  =  60  grains. 

1  ounce  =  480  grains. 

1  pound  =  12  ounces  =  5760  grains. 


Troy. 

1  pennyweight  =  24  grains. 

1  ounce  =  20  dwt.  =  480  grains. 

1  pound  =  12  ounces  =5700  grains. 


Decimal  Weights  authorized  T)y  Congress. 

A  thousand  milligrammes  make  one  gramme. 

A  thousand  grammes  “  “  kilogramme. 

One  grain  corresponds  to  65  milligrammes  nearly  (64.8). 

One  drachm  apothecaries’  weight  to  3.882  grammes. 

“  ounce  “  “  31.1035  “ 

“  “  avoirdupois  “'28.349  “ 

“  pound  “  “  453.59  “ 

“  “  apoth.  or  troy  373.242  “ 


1  gramme  =  15.43234  grains. 

1  kilogramme  =2  lbs.  3  oz.  119.85  grs.,  or  15,432.35  g 


jr 


422 


CHEMICAL  MANIPULATIONS. 


Measuring  is  still  more  liable  to  error 
than  weighing.  The  vessel  must  be  kept 
carefully  perpendicular,  and  be  examined 
by  a  level  light.  The  surface  of  the  liquid 
is  always  curved,  being  higher  at  the  edges. 
The  lower  level  is  that  to  be  used,  that  is, 
the  lower  part  of  the  curved  surface  must 
correspond  with  the  lines  ruled  on  the 
glass,  as  shown  by  the  dotted  line  on  the 
figure,  which  represents  a  “minim  glass.” 

Liquid  Measure. 

1  fluid rachm  =  60  minims. 

1  fluidounce  =  8  fluidraclims. 

1  pint  =  16  fluidounces. 

1  gallon  =  8  pints. 

§  2. — Heating. 

The  alcohol  lamp  was  for  a  long  time  the  favorite  source  of  heat 
when  needed  on  a  small  scale ;  its  advantage  lies  in  its  high  tem¬ 
perature  and  freedom  from  smoke.  As  alcohol  both  evaporates 
and  absorbs  water  from  the  air,  the  wick  should  be  kept  covered. 
If  the  wick-tube  is  passed  through  a  cork,  this  should  always 
have  a  groove  to  permit  escape  of  vapor,  or  it  will  be  liable  to 
be  driven  out  with  a  dangerous  explosion. 

But  whenever  gas  can  be  had,  the  Bunsen  burner  (see  Fig.  144) 
convenient^  and  economically  replaces  alcohol. 

The  sand-bath  is  an  excellent  means  of  applying  a  gentle  heat 
to  large  surfaces. 

A  very  simple  and  convenient  form  of  sand-bath  is  to  have  a 
circular  rim  on  top  of  a  stove,  filled  with  clean  building  sand. 
The  heat  is  thus  applied  much  more  evenly  than  if  the  vessel  were 
set  directly  on  the  stove  without  the  interposition  of  the  sand,  and 
the  danger  of  breakage  is  greatly  diminished. 

A  sand-bath  may  also  be  established  over  a  Bunsen  burner. 
Get  a  worker  in  sheet-iron  to  make  a  cylinder  of  stout  galvanized 
iron,  about  twelve  inches  in  diameter,  and  ten  high.  The  top 
and  bottom  are  turned  over  heavy  iron  wire,  and  curved  pieces 
are  cut  out  at  top  and  bottom,  to  serve  as  air-passages.  A  circular 
piece  of  sheet-iron  is  hammered  into  a  basin  thirteen  inches 
across,  and  this,  filled  with  sand,  rests  on  the  top  of  the  cylinder. 
Such  a  ..cylinder  will  support  a  very  heavy  weight. 


Fig.  143. 


EVAPORATION. 


423 


§  3. — Evaporation. 

In  evaporating,  two  important  points  are  to  be  borne  in  mind. 
First,  the  heat  should  not  be  contracted  to  a  single  point ;  and 
second,  it  should  not  be  so  diffused  as  to  strike  that  part  of  the 
vessel  that  is  above  the  liquid.  In  either  case  fracture  is  apt  to 
occur;  in  the  latter  case,  almost  certainly. 

For  large  operations  the  sand-bath  will  be  proper ;  that  is,  for 
evaporating  negative  baths,  and  such  work.  For  small  operations 
the  following  arrangement  is  capital. 

Procure  a  lampstand,  with  a  strong 
ring  about  five  inches  in  diameter; 
take  a  piece  of  strong  but  fine  and 
close-meshed  brass  wire  gauze,  six 
inches  square,  lay  it  on  the  ring  and 
press  the  corners  down  under  the  ring, 
so  as  to  fix  it  firmly  to  it.  This 
wire  gauze  forms  a  support  which  will 
carry  anything  from  a  capsule  an  inch 
in  diameter  to  a  basin  of  twelve  or 
fifteen  inches,  provided  the  lampstand 
be  strong  and  stout  as  it  should  be,  as 
well  as  flasks,  beakers,  or,  in  fact,  any  utensil  whatever.  The 
Bunsen’s  burner  stands  under  this,  always  ready  for  service  at  a 
moment’s  notice.  The  wire  gauze  stops  the 
flame,  and  permits  only  the  hot  air  to  pass 
through,  thus  giving  a  great  protection  against 
accident,  whilst  scarcely  interfering  with  the 
heating. 

A  tripod ,  if  made  strong  and  stout,  is  also 
a  good  support,  but  far  less  convenient  than 
the  foregoing,  inasmuch  as  it  cannot  be  raised 
and  lowered,  and  is  never  so  strong  as  the  lampstand.  In  this 
case,  also,  a  piece  of  wire  gauze,  should  be  interposed  between 
the  vessel  and  the  source  of  heat. 


Fig.  145. 


§  4. — Filtration. 

Of  filtration ,  all  that  need  be  said  is,  make  the  filter  always  a 
little  smaller  than  the  funnel,  and  always  wet  it  before  pouring 
in  the  liquid  to  be  filtered.  Select  a  good  paper,  which  filters 


424 


CHEMICAL  MANIPULATIONS. 


clean  and  quickly,  and  when  that  which  exactly  suits  is  found, 
a  good  supply  should  be  laid  in.  Nothing  is  more  vexatious 
than  to  wait  for  a  slow  filtration. 

§  5. — Pouring. 

In  transferring  liquids  from  one  vessel  to  another,  there  are 
two  contrivances  by  which  the  clean 
performance  of  the  operation  without 
loss  may  be  greatly  facilitated.  These 
are  greasing  and  rod-pouring. 

Greasing  is  the  application  of  a  little 
tallow  on  the  finger  under  the  lip  over 
which  the  liquid  is  to  be  poured.  For 
pouring  valuable  liquids  out  of  large 
vessels,  especially  if  nearly  full,  this 
mode  is  very  useful. 

In  rod-pouring ,  the  glass  rod  is  first 
wetted  with  the  liquid,  and  is  then  held 
to  the  lip  of  the  vessel,  which  is  so  in¬ 
clined  as  to  pour  slowly,  the  stream  following  the  rod  (Fig.  140). 
Both  methods  may  be  combined. 


Fig.  146. 


§  6. — Fusing. 

For  reducing  chloride  of  silver  in  the  dry  way,  a  Hessian  cru¬ 
cible  may  be  used.  The  chloride  is  intimately  mixed  with  twice 
its  weight  of  dry  carbonate  of  sodium ;  this  mixture  is  rammed 
tightly  into  the  crucible,  which  is  by  degrees  raised  to  a  white 
heat.  As  the  Hessian  crucibles  are  porous,  some  of  the  silver 
may  sink  in.  To  obviate  this,  fuse  a  little  borax  in  it,  or  use  a 
Paris  clay  crucible,  which  is  not  liable  to  this  objection. 

For  fusing  nitrate  of  silver,  a  Berlin  or  Meissen  porcelain  basin 
will  be  required ;  none  other  can  be  depended  upon.  The  Ber¬ 
lin  are  the  best,  and  are  stamped  in  blue;  some  with  the  letters 
K  P  M,  some  with  a  Prussian  eagle  inside  of  a  circle.  Both  of 
these  sorts  are  excellent.  With  care,  the  operation  is  perfectly 
safe,  and  fracture  need  not  be  feared.  The  Bunsen  burner  will 
give  the  necessary  heat  for  small  quantities,  or  combined  burners 
for  large. 


NEUTRALIZATION. 


425 


g  7. — Neutralization. 

Where  the  object  is  merely  to  render  an  alkaline  liquid  acid,  or 
an  acid  one  alkaline,  it  will  be  sufficient  to  add  the  appropriate 
reagent,  until  blue  litmus-paper,  by  turning  red,  indicates  acidity ; 
or  red,  by  becoming  blue,  shows  alkalinity,  as  the  case  may  be. 

But  an  exact  neutralization,  as  where  an  acid  or  an  alkaline 
liquid  is  to  be  rendered  exactly  neutral,  is  an  operation  requiring 
some  circumspection.  If,  for  example,  an  acid  liquid  is  to  be 
neutralized  with  ammonia,  and  the  latter  liquid  is  added  a  few 
drops  at  a  time,  the  operation  will  be  very  tedious,  and  will  be 
almost  certain  to  fail,  an  excess  of  ammonia  will  almost  certainly 
be  at  last  introduced.  The  operator,  therefore,  feels  his  way.  He 
pours  off  a  part,  say  a  third,  of  the  acid  liquid,  and  adds  boldly 
enough  ammonia  to  make  it  quite  alkaline.  He  then  adds  enough 
of  the  remainder  of  the  original  liquid  to  render  the  mixture 
decidedly  acid.  Bepeating  this  several  times,  he  gets  a  pretty 
clear  idea  of  the  proportion  of  ammonia,  unknown  at  first,  which 
is  required.  Towards  the  end  he  diminishes  the  quantity  of  each 
successive  addition,  till  with  the  last  drops,  with  care,  he  obtains 
an  exact  neutralization. 

There  are  some  cases  in  which  the  neutralization  is  effected 
by  the  addition  of  a  substance  which,  even  if  added  in  excess, 
produces  a  precipitate,  and  so  leaves  the  solution  neutral,  so  that 
the  addition  of  an  excess  of  the  precipitant  is  without  much  im¬ 
portance.  An  example  of  this  is  presented  in  the  neutralization 
of  an  acid  negative  bath  with  carbonate  of  sodium.  If  an  excess 
of  carbonate  of  sodium  be  added  beyond  what  is  necessary  to 
neutralize  the  free  acid,  carbonate  of  silver  is  formed,  and  this 
being  but  very  sparingly  soluble  in  water,1  is  precipitated.  The 
addition,  therefore,  of  a  slight  excess  of  carbonate  of  sodium  does 
not  render  the  liquid  more  than  very  faintly  alkaline. 

In  other  cases,  the  neutralization  is  effected  by  a  substance 
insoluble  in  the  solution  after  neutralization.  This  is  the  simplest 
case  of  all :  it  is  sufficient  to  add  the  neutralizing  substance  in 
excess,  and  then  to  remove  that  excess  by  filtration.  An  example 
of  this  is  afforded  in  the  preparation  of  a  neutral  gold  toning- 
bath.  The  acid  solution  of  perchloride  of  gold  is  agitated  with 
excess  of  precipitated  chalk ;  as  much  chalk  dissolves  as  is  neces- 

1  Soluble  in  31,978  parts  of  water  at  12°  C.  (Kremers.) 

23 


426 


CHEMICAL  MANIPULATIONS. 


sary  to  neutralize  the  excess  of  hydrochloric  acid,  and  the  rest 
is  got  rid  of  by  filtration. 

Negative  baths  requiring  neutralization  must  always  be  treated 
with  bicarbonate  of  sodium,  never  with  chalk. 


\  8. — Decantation. 


Fig.  147. 


In  all  cases  where  a  precipitate  is  to  subside,  that  ope¬ 
ration  takes  place  best  in  vessels  larger  at  the  bottom 
than  at  the  top,  tolerably  well  in  vessels  with  straight 
sides,  and  very  badly  in  conical  vessels,  widening 
towards  the  top.  Those  of  this  last  shape  should,  there¬ 
fore,  never  be  employed  for  decantation.  The  shape 
shown  in  the  margin  is  the  proper  one. 


§  9. — Cleaning  Glass  and  Porcelain  Vessels. 


The  bichromate  mixture  already  recommended  for  cleaning 
glass  plates  is  most  excellent  for  vessels.  It  should  be  pretty 
strong.  A  most  useful  plan  is  to  take  cold  saturated  solution  of 
bichromate  of  potash,  and  add  about  one-eighth  its  bulk  of  sul¬ 
phuric  acid  (or  one-fourth  its  bulk  of  the  dilute  acid  that  comes 
from  the  drying-box).  If  the  ordinary  acid  is  used,  it  must  be 
mixed  in  a  porcelain  or  thin  glass  vessel ;  a  bottle  will  probably 
break  by  the  sudden  heat  evolved.  For  a  few  moments  a  corro¬ 
sive  vapor  is  thrown  off;  after  cooling,  however,  this  trouble 
disappears. 

About  a  quart  of  this  mixture  is  to  be  kept  on  hand  and  poured 
into  vessels  needing  cleaning,  which  it  does  very  effectually.  It 
may  be  used  again  and  again  until  it  takes  a  brownish-violet 
color,  when  it  should  be  rejected  as  spent. 


§  10. — Marking  Negatives. 

The  photographer  will  often  desire  to  mark  his  negatives,  es¬ 
pecially  landscapes,  with  the  name  of  the  place,  the  lens  used,  or 
other  note  of  interest.  With  portraits  there  are  always  places 
convenient  for  either  marking  with  black  varnish,  or  marking 
with  a  sharp  point  through  a  dense  place,  on  portions  not  to  be 
used  in  the  print.  But  with  a  landscape  negative,  good  to  the 
very  edge,  one  is  not  disposed  to  sacrifice  a  place  for  marking. 


BENDING  GLASS. 


427 


An  excellent  plan  is  to  use  a  writing  diamond ,  which  is  quite  dif¬ 
ferent  from  a  glazier’s,  and  may  be  had  of  the  philosophical 
instrument  makers.  With  one  of  these  one  may  write  legibly 
on  the  back,  over  a  very  thin  or  a  very  thick  portion,  without 
the  marks  showing  in  the  print,  as  is  the  case  when  a  glazier’s 
diamond  is  used.  These  writing  diamonds  are  sparks  set  in  steel 
tubes  much  like  everpoint  pencils.  They  are  mostly  made  in 
Amsterdam,  the  great  centre  of  diamond-cutting. 


§  11. — Bending  Glass. 

An  ordinary  gas  flame  is  sufficient  for  bending  glass  tubes  up 
to  half-inch  diameter.  No  particular  care  is  necessary  except  to 
apply  the  heat  equally  by  slowly  turning  the  tube  round,  and  to 
avoid  commencing  to  bend  until  the  glass  is  quite  soft,  otherwise 
the  tube  will  almost  certainly  break.  The  black  from  the  flame 
will  easily  wipe  off.  Lay  the  bent  tube  on  some  non-conducting 
surface  to  cool  slowly. 


§  12. — Piercing  Holes  in  Corks. 


This  is  best  done  with  borers  Fig.  148. 

consisting  of  tubes  of  brass  or 
tinned  iron.  The  former  are  to 
be  had  of  the  instrument  makers, 
in  sets  of  different  sizes  sliding 
into  each  other.  The  tin  tubes 
can  be  made  by  any  tinsmith,  and 
should  have  a  cross-piece  as  a 
handle  across  one  end.  This  end- 
piece  has  a  hole  cut  into  it  of  the 
same  size  as  the  tube,  in  order 

that  the  pieces  of  cork  punched  out  may  pass  freely  through. 
Several  sizes  will  be  wanted,  say  x3g,  T4g,  T6g,  J,  f,  1  inch.  A  set 
of  a  dozen  comprising  other  intermediate  sizes  is  still  more  satis¬ 
factory.  The  edges  should  be  occasionally  sharpened  with  a  rat- 
tail  file. 


428 


CHEMICAL  MANIPULATIONS. 


§  13.— Softening  Corks. 

All  corks  are  the  better  for  softening.  The  cork-pressers 
usually  sold  are  next  to  worthless.  To  roll  the  cork  under  the 
foot,  with  a  piece  of  clean  paper  above  and  below  it,  is  not  a  bad 
way,  but  the  circular  cork-pressers,  consisting  of  a  notched  wheel 
and  excentric  band,  are  most  excellent.  A  cork  should  be  soft¬ 
ened  before  boring,  not  after. 


§  14. — Blackening  Brass  and  Wood  Surfaces. 

Brass. — Dissolve  a  drachm  of  bichloride  of  platinum  in  one 
ounce  or  one  and  a  half  ounce  of  water,  and  add  a  grain  of  nitrate 
of  silver.  Clean  and  polish  the  brass  surface,  warm  it,  and  apply 
the  solution  with  a  small  tuft  of  cotton.  Eub  till  dry,  and  then 
finish  off  with  a  little  dust  of  graphite,  avoiding  to  put  on  any 
polish,  which  would  convert  the  surface  into  a  reflecting  one, 
and  enable  it,  though  black,  to  send  back  white  light. 

Brass  surfaces  are  cleaned  for  these  purposes,  either  by  rubbing 
with  sand  and  polishing  powder,  or  by  applying  nitric  acid.  The 
fumes  that  rise  should  be  carefully  avoided,  anji  the  acid  be  only 
left  on  till  a  bright  surface  is  obtained. 

Wood. — Take  five  parts  of  lampblack,  two  of  finely  pulverized 
gum-arabic,  and  one  of  brown  sugar ;  mix  to  a  thick  paste  with 
water,  and  rub  on  with  a  piece  of  flannel.  This  is  excellent  for 
the  insides  of  cameras  and  drying-boxes  ;  it  does  not  come  off*  on 
the  fingers.  A  second  coat  aids  in  obtaining  a  perfect  blackness. 
If  it  soils  the  finger  when  rubbed  on  it,  there  was  too  much 
lampblack;  if  there  show  itself  any  reflection,  there  was  too  little. 

§  15. — Paste. 

Paste  is  far  preferable  to  mucilage  for  attaching  labels.  If 
well  boiled,  and  then  mixed  with  a  little  carbolic  acid  (one 
drachm  to  eight  or  ten  ounces  of  paste),  and  placed  in  a  bottle 
with  a  cork  pierced  to  carry  a  brush,  it  will  keep  in  excellent 
condition  for  a  year  or  more.  When  gum  mucilage  is  used,  the 
addition  of  a  very  little  glycerine  will  make  it  hold  better,  and 
diminish  its  tendency  to  separate  or  “scroll.” 


buckle’s  brush. 


429 


§  16. — Filtration  of  Viscid  Liquids — the  Percolator. 

Solutions  of  gum,  of  gelatine,  and  other  viscid  liquids,  are  best 
filtered  through  a  percolator.  This  is  a  porcelain 
funnel  without  a  neck,  and  pierced  with  twelve 
oval  openings.  It  is  so  set  into  a  jar  that  all 
the  openings  shall  be  below  the  upper  rim  of 
the  jar.  A  paper  or  other  filter  is  placed  inside. 

When  paper  is  used,  it  is  best  to  make  the 
lower  part  of  the  paper  double,  by  putting  in  a 
second  and  smaller  filter  to  prevent  bursting  at 
the  bottom.  The  facility  of  filtering  through 
the  percolator  greatly  exceeds  that  of  an  ordinary  filtering 
funnel. 


Fie.  149. 


§  17.— Buckle’s  Brush. 

A  string  is  passed  over  a  tuft  of  cotton,  and  the  end  of  the  tuft 
is  pulled  by  the  string  into  a  glass  tube.  This  sort  of  brush  has 


Fie.  150. 


been  largely  used  for  extending  solution  of  nitrate  of  silver,  and 
other  solutions,  over  paper.  When  soiled,  it  is  easy  to  change 
the  cotton  for  a  fresh  piece. 


NOTES  AND  ADDENDA. 


Permanent  Silvered  Paper  (see  p.  277). — At  the  time  when  the  article  on  the 
author’s  new  process  in  the  body  of  this  manual  went  to  press,  there  had  been 
so  far  time  only  for  testing  its  keeping  qualities  about  seven  weeks.  Since  then, 
the  paper  has  been  used  after  keeping  it  for  over  three  months ,  with  entire  success, 
and  the  great  value  of  the  -method  has  been  fully  confirmed.  As  already  men¬ 
tioned,  when  the  paper  is  long  kept,  it  acquires  a  slight  yellowish  tinge  on  the 
face,  and  a  light  brownish  coloration  on  the  back ;  but  as  these  disappear  in 
the  operations  of  toning  and  fixing,  when  carried  through  precisely  in  the  ordi¬ 
nary  manner,  they  have  no  importance.  The  prints  executed  on  paper  kept 
over  this  long  period  are  not  to  be  distinguished  from  those  made  immediately 
after  sensitizing. 

The  object  of  this  process  is  not,  however,  so  much  to  keep  paper  over  these 
long  periods,  as  to  enable  those  who  work  on  a  small,  or  even  on  a  moderate 
scale,  to  avoid  the  trouble  of  daily,  or  almost  daily,  preparation  of  small  quantities 
of  paper ;  even,  however,  for  those  who  operate  more  largely  the  process  has  its 
advantages  in  the  avoidance  of  waste  such  as  constantly  results  from  miscalcula¬ 
tion  and  from  unexpected  changes  of  weather,  by  which  vexatious  losses  are  a 
common  experience.  It  should  be  remarked  that  the  experiments  here  described 
were  made  during  the  moderate  weather  of  spring,  and  that  in  hot  summer 
weather  the  time  during  which  the  paper  can  be  kept  may  not  reach  so  great  a 
length. 

The  writer  desires  also  again  to  call  attention  to  the  fact,  that  all  paper  prepared 
by  any  process  with  the  intention  of  long  keeping,  should  be  sensitized  with  much 
more  careful  exclusion  of  light  than  is  necessary  for  paper  intended  for  immediate 
use.  Similar  care  is  necessary  when  the  box  containing  it  is  opened  to  take  out 
part  of  the  paper,  in  order  that  what  remains  over  shall  not  have  been  exposed 
to  light.  It  is  best  to  do  this  in  the  dark  room. 

Water-proof  Negative  Varnish. — Since  the  remarks  on  p.  375,  &c.,  went  to 
press,  there  has  been  time  to  extend  the  observations  on  the  resistance  of  these 
varnishes  over  a  longer  period.  After  the  plates  had  been  left  for  three  months 
under  water,  they  were  in  the  following  conditions  : — 

The  bleached  lac  varnish  (No.  1),  and  one  of  the  orange  lac  varnishes 
(No.  8),  were  in  good  condition,  and  exhibited  no  signs  of  injury  except  that  each 
had  a  small  pucker  or  fold  at  one  corner,  so  slight  as  to  have  no  real  importance. 

The  other  orange  lac  varnish  (No.  2)  was  in  an  entirely  perfect  condition. 

Sandarac  varnish  (No.  4)  was  badly  torn,  about  one-third  the  film  was  off  the 
plate. 

The  resisting  powers  of  all  these  four  varnishes  cannot  be  considered  as 


432 


NOTES  AND  ADDENDA. 


otherwise  than  very  remarkable,  for  even  the  Sandarac  stood  for  a  long  time, 
and  though  inferior  to  the  other  three  in  its  resistance  to  moisture,  excelled 
them  in  resistance  to  heat  and  to  mechanical  injuries. 

The  observation  has  been  often  made,  that  out  of  a  lot  of  negatives  made  at 
the  same  time,  and  varnished  with  the  same  varnish,  and  kept  under  identical 
conditions,  some  will  be  ruined  with  honeycomb  cracks  and  others  escape,  and 
this  fact  has  occasioned  much  surprise,  and  has  remained  unexplained.  The 
writer  is  satisfied,  from  his  examination,  that  the  explanation  is  very  simple. 

Varnish  penetrates  but  slowly  through  a  collodion  film,  and  if  it  is  poured  off* 
too  soon,  the  negative  may  appear  to  be  all  right,  and  yet  the  varnish  have 
really  no  sufficient  hold  upon  the  glass.  The  importance  of  this  point  has,  the 
writer  believes,  never  before  been  pointed  out.  In  the  directions  for  varnishes 
given  in  this  manual,  it  is  advised  to  wait  ten  or  twelve  seconds  after  the  plate  is 
completely  covered ,  before  commencing  to  pour  off.  This  gives  the  varnish  time 
to  completely  saturate  the  film  and  to  cover  the  glass  under  the  film  with  an  even 
stratum.  Attention  to  these  directions  is  important,  especially  for  those  who  wish 
to  feel  that  their  negatives  are  safe  for  a  long  period  of  years. 

It  seems  scarcely  necessary  to  say  that  if  the  hyposulphite  has  not  been 
thoroughly  washed  out,  the  dangers  to  the  negative  are  thereby  much  aggra¬ 
vated.  Experience  is  also  constantly  accumulating  to  show  that  when  negatives 
have  been  carelessly  varnished,  or  where  a  poor  varnish  has  been  used,  any 
sudden  change  of  hygrometric  condition  may  cover  the  negative  with  honey¬ 
comb  cracks.  A  case  has  been  cited  in  which  a  negative  in  good  condition  was 
taken  from  a  warm,  dry  room  and  carried  for  half  an  hour  through  a  damp 
atmosphere,  at  the  end  of  which  time  it  was  covered  with  cracks.  With  any  of 
the  above  four  varnishes  properly  applied,  it  is  safe  to  say  that  such  a  trial  might 
have  been  repeated  a  score  or  perhaps  a  hundred  times  without  evil  results. 

When  this  trouble  occurs,  the  writer  would  advise  to  revarnish  with  a  thin 
spirit  varnish,  leaving  it  in  for  twenty  or  thirty  seconds  before  commencing  to 
pour  off.  In  his  own  work  he  has  never,  met  with  a  single  case  of  cracking. 

Reducing  Residues. — Lately  the  plan  of  precipitating  silver  as  oxalate  and 
reducing  by  heat,  has  been  brought  forward  again.  The  idea  is  ingenious,  and 
as  oxalate  of  silver  is  easily  resolved  into  metallic  silver  by  the  simple  application 
of  heat,  the  method  would  be  convenient  enough,  were  it  not  so  dangerous.  The 
oxalate  of  silver,  when  heated,  is  liable  to  explode  with  tremendous  violence  ;  an 
accident  of  this  sort  happened  some  years  ago  in  the  laboratory  of  M.  Wurtz,  in 
Paris. 

New  Developer. — It  is  stated  that  the  action  of  pyrogallic  acid  as  a  developer  is 
greatly  heightened  by  the  addition  of  sulphate  of  copper.  A  tliree-grain  solution 
of  pyrogallic  acid  is  mixed  with  one-tliird  of  its  bulk  of  a  cold  saturated  solution 
of  sulphate  of  copper  just  before  throwing  it  over  the  plate. 


INDEX 


A, 

Aberration,  58,  59 
Accessories,  203 

arrangement  of,  189 
Acceleration  of  exposures,  220 
Acetate  toning,  290 
Adapting  flanges,  224 
Admission,  centre  of,  69 
After-intensification,  171 
Alabastrine  positives,  189 
Albertype,  394 

Albumen  positives  on  glass,  by  de¬ 
velopment,  387 
by  sun  printing,  391 
Albumenizing  glass,  155 
paper,  270 

Alcohol,  influence  of,  131 
Alkaline  carbonate  toning,  289 
development,  358 
Alum  in  the  printing  bath,  274 
Ambrotypes,  42,  188 
Aniline  process,  396 
Animals  photographed,  349 
Annatto  for  backing,  356 
Anthony,  H.  T.,  alum  in  printing 
bath,  274 
fuming,  279 
Aplanatic  lens,  10,  81 
Apparent  size  of  objects,  106 
Architectural  photography,  208 
Arrangement  of  accessories,  191 
Arrowroot  paper,  272 
Astigmation,  61 
Atmospheric  effect,  244 

B. 

Backgrounds,  203 
canopy,  204 
conical,  205 


Backgrounds — 
crayon,  208 
inclined,  204 
pictorial,  208 
rotating,  206 
Backing  dry  plates,  356 
Balance,  421 
Bar  frame,  45 
Barrel  distortion,  65 
Bases  in  collodion,  134 
Bath,  fixing,  46 

negative,  19,  155 
positive,  44 
printing,  273,  274 
swinging,  158 
toning,  46 
Bending  glass,  427 
Benzoate  toning,  290 
Berlin  portraits,  194,  283 
Blackening  brass  and  wood  sur¬ 
faces,  428 

Blistering  in  dry  plates,  352 
silver  prints,  341 
Blotting  off  silvered  paper,  274 
Blue  stippling,  121 
Blurring,  27,  315 
Brass  surfaces,  to  blacken,  428 
Brilliancy,  how  obtained,  231 
Bromide  of  ammonium,  134 
of  cadmium,  136 
of  lithium,  135 
of  potassium,  134 
of  sodium,  135 

Bromides  in  collodion,  137,  168 
Buckle’s  brush,  429 

C. 

Calcio-chloride  toning,  289 
Camera,  landscape,  147 
levelling  the,  147 


434 


INDEX. 


Camera — 

red  lining  to,  221 
reversing  of,  148 
selection  of,  12,  147,  221 
solar,  printing  by,  268 
tested,  13 

for  transparencies  and  opalo- 
types,  384,  385 
Van  Monckhoven’s,  266 
Woodward’s  solar,  266 
Canopy  background,  204 
Carbon  printing,  298,  402 
on  glass,  403 

Carbonate  of  silver,  printing  on, 

282 

Carriers,  14 

Centre,  admission  and  emission,  69 
optical,  68 
Chemicals,  15 
in  fault,  304 
Chemical  focus,  95 
Chloride  of  iron,  printing  witli^  398 
of  silver,  development  on,  160 
Chlorine,  intensifying  by,  172 
Chromatic  aberration,  59 
Cleaning,  35 
glass,  426 
Cleanliness,  17 
Clouds,  219,  239 
printed  in,  184 
reflected,  185 
Clove  process,  373 
Coating  the  plate,  23 
Coffee  process,  371 
Collo-developers,  164 
Collodio-bromide  process,  365 
Collodio-chloride  process — 
failures  in,  242 
on  glass,  388 
on  paper,  391 
Collodion,  131,  231,  305 
decanting,  145 
dry  plate,  365 
filtering,  146,  367 
formulas  for,  142,  143 
injurious  to  health,  416 
keeping  of,  146 
salting,  132,  134 
thinning,  25 

Colors  obtained  in  photography, 
414 


Coma,  63 
Comets,  324 

Combination  prints,  182 
Composition,  234 
Conical  background,  204 
Conjugate  foci,  75 
Contact  printing  on  glass,  386 
Contrast,  causes  of,  165,  313 
in  composition,  243 
Contrasts,  213 
Copying,  251 

camera,  253,  255 
cone,  253 

Corks,  to  pierce,  427 
to  soften,  427 

Corrosive  sublimate  for  intensify¬ 
ing,  172 

Corrosive  sublimate,  poisonous  ef¬ 
fects  of,  417 
Cotton,  negative,  126 
Crapy  lines,  310 
Crayon  portraits,  194 
Cross-lights,  193 
Creamy  negatives,  161 
Curvature  of  the  field,  63 
Cut-off,  15 

Cyanide  for  intensifying,  173 
poisonous  nature  of,  416 

D. 

Daguerreotypes,  copying  of,  254 
Dark  room,  109 

arrangement  of,  111 
temperature,  113 
Decantation,  426 
Defects  in  the  image,  313 
Developers,  Collo-,  164 
strong  and  weak,  162 
sugar,  164 

Developing  boxes,  346 
Development,  30,  132,  162,  305 
aids  to,  162,  163 
alkaline,  358 
of  dry  plates,  358 
management  of,  165,  166,  198, 
200,  214,  318,  432 
on  paper,  260 
Diagonal  line,  the,  236 
Diaphragms,  64,  92 
inclined,  66,  219 


INDEX. 


435 


Difficulties  in  portraiture,  198 
Dippers,  25 
Direction,  line  of,  234 
Dispersion,  54 

Distance  in  landscape  composition, 

238 

Distance  of  position,  191 
Distortion,  65 
Double  portraits,  181 
Drawings,  copying  of,  251 
Dress,  effect  of,  196 
Dry  plate  photography,  351,  365 
plates,  to  dry,  353 
backing  of,  356 
development  of,  358 
failures  in,  360 

Drying  box,  the  author’s,  354 
Drying  dead,  330 
Drying  plates  by  heat,  353 
spontaneously,  356 
by  sulphuric  acid,  354 
Dust,  160 

E. 

Edging  plates,  352 
Emission,  centre  of,  69 
Enamels  burned  in,  392 
Encaustic  paste,  300 
Engravings,  copying  of,  251 
Enlargements,  177,  265 
Equivalent  focus,  70 
Ether,  influence  of,  131 
injurious  effects  of,  415 
Evaporating,  423 
Exposure,  30,  195 

acceleration  of,  220 
of  dry  plates,  361,  363 

F. 

Failures  in  dry  plate  work,  360 
in  photographic  operations,  301 
in  silver  printing,  337 
in  varnishing,  40,  330 
Faults  in  spherical  lenses,  58 
Feathery  markings,  330 
Fennemore’s  glass  room,  118 
Ferrotypes,  42,  188 
Field  work,  222 
Figure,  relative  size  of,  192 


Figures  in  landscapes,  241 
Filtering  collodion,  146,  367 
Filtration,  423 
Fixing  the  print,  293 
Fixing  bath,  46 
Flanges,  96,  224 
Flare,  91 

Flat  pictures  avoided,  199 
Focal  lengths  of  lenses,  66 

determined,  70,  72,  73,  74 
Foci,  conjugate,  75 
Focus,  chemical,  95 

equivalent  or  absolute,  70 
Focussing,  28,  224 
Fogging,  302 

of  dry  plates,  362 
sources  of,  112, 113 
Foliage,  219 

Foreground  in  landscapes,  219,  237 
Fuming,  279 
Fusing  residues,  424 

G. 

Gallate  of  lead,  261 
Ghost  in  the  camera,  91 
Ghosts,  181 

Glass,  cleaning  of,  17,  155 
for  glass  house,  115 
ground,  48,  121 
preparing  of,  155 
selection  of,  154 
Glass  room,  115 
Globe  lens,  85 

Glycerine  and  honey  process,  350 
Gold,  chloride  of,  a  poison,  418 
Gold  residues  saved,  381 
Groups,  120,  192,  248 
Granularity  in  negatives,  310 
Green  color,  its  actinic  value,  139 
Ground  glass,  printing  under,  180, 
283 

Gum  in  dry  plate  work,  365 
Gum-gallic  process,  374 
Gurney’s  glass  room,  119 

H. 

Halation,  315 

Half-tone,  how  obtained,  167,  315 


486 


INDEX. 


Harsh  pictures  avoided,  199 
Health,  415 

Heat  in  development,  359 
Heating,  422 
Heliochromy,  414 
Holders,  pneumatic,  159,  160 
Horizon  in  landscapes,  242 
Hyposulphite  of  sodium,  testing 
for,  297 


I. 

Illumination,  201 
Image  defective,  313 
nature  of,  97 

Inclined  backgrounds,  203,  204 
Index  of  refraction,  54 
Instantaneous  photography,  347 
Intensifying  negatives,  171,  172,  173 
Intensity,  falling  off  of,  at  edges,  65 
Iodides  in  collodion,  137 
Iodine  for  intensifying,  171 
Irregularity  of  film,  310 
Iron,  printing  with  salts  of,  397 
Ivory,  miniature  effects  on,  390 


J. 

Jamin  lenses,  80 


L. 

Landscape  lenses,  9,  91 

photography,  11,  51,  208,  224 
Legray’s  process,  264 
Lenses,  aplanatic,  10,  81 

Blunt’s  hemispherical,  88 
care  of,  9(3 
centering  of,  93 
comparison  of,  92 
focal  lengths  of,  66 
general  remarks  on,  90 
globe,  85 
images  of,  97 
Jamin,  80 
nature  of,  56 
orthoscopic,  87 
Pantascope,  88 


Lenses — 

portrait,  79 
quickness  of,  95 
rapid  rectilinear,  9,  81 
rectilinear,  88 
Ross’s  doublet,  87 
selection  of,  9,  93 
triplet,  83 
view,  9,  78 
Zentmayer,  86 

Levelling  the  camera,  29,  209 
Liesegang,  toning  formula,  291 
Light,  exclusion  from  lens,  120 
influence  of,  250 
insufficient,  202 
management  of,  193,  200 
regulation  of,  109,  124 
Line  engravings,  copying  of,  251 
Lines  in  the  negative,  326 
Lithographs,  copying  of,  251 
Local  redevelopment,  169 

reduction  of  negatives,  176 
Loescher  &  Petzch’s  glass  room, 
119 

Lumps  in  the  film,  311 


M. 

Magnesium  light,  negatives  by,  185 
Management  of  light,  193 
Manipulations,  420 
in  the  field,  222 
Marbled  stains,  327 
Materials  for  landscape  work,  221 
Measuring,  422 
Meicke’s  experiments,  275 
Melainotypes,  189 
Mercury  for  intensifying,  172,  174 
Metrical  weights,  421 
Mezzotint  prints,  194,  283 
Mezzotints,  copying  of,  251 
Microphotography,  258 
Microscopic  photography,  259 
Miniature  effects  on  ivory,  390 
Minim  glass,  422 
Miscellaneous  faults,  333 
Moonlight  effects,  181 
Morphia  process,  374 
Mottling  in  the  negative,  312 
Mounting  prints,  299 


•* 


INDEX. 


437 


N. 

Negative,  the,  147,  158 
artifices  with,  181 
bath,  19,  155,  304 
development  on  paper,  263 
drying  of,  37 
for  enlargement,  177 
influences  on,  167 
intensifying  of,  171,  172,  173,  174 
by  magnesium  light,  185 
marking  of,  426 
paper  pasted  on,  180 
printing  of,  280 

reducing  of  over-developed,  176 
locally,  176 
retotiching,  178 
reversed,  400 
scarlet,  173 
storing  of,  186 
thin,  how  printed,  281 
varnished,  to  intensify,  175 
varnishing  of,  37,  375,  431 
washing  of,  36 
Neutralization,  425 
Nitrate  of  silver,  fused,  157,  305 
Nitric  acid,  poisonous  effects  of, 
418 

Nitroglucose,  268 
Notman,  toning  formula,  290 

O. 

Objectives,  9 

Oil  paintings,  copying  of,  251 
Opalotypes,  383 
Optical  centre,  68 
Orthoscopic  lens,  87 
Out-door  photography,  344 
Oxalotype,  398 
Oyster-shell  markings,  327 

P. 

Pads,  45 
Pad  fuming,  279 
Panoramic^amera,  88 
Paper,  albumenizing,  270 
arrowroot,  272 
enlargements,  265 


Paper — 

negatives,  263 
for  positives,  269 
sensitizing  of,  273 
Papyroxyline,  Liesegang’s,  129 
Paraffining,  264 
Paste,  428 

encaustic,  300 

Pencil  drawings,  copying  of,  251 
Percolator,  429 

Permanence  of  silver  prints,  300 
Permanganate  of  potassium,  174 
Perspective,  atmospheric,  244 
incorrect,  103 
photographic,  97 
Photogalvanography,  395 
Photography,  architectural,  208 
landscape,  208 

Photographs,  copying  of,  254 
Photolithography,  394 
Pinholes,  321 
Plans,  copying  of,  255 
Plate  boxes,  187 
Plates,  preserved,  350 

sensitive,  keeping  of,  344 
Pneumatic  holders,  159,  160 
Poisons,  415 
Portrait  lenses,  10,  79 
Portraiture,  90,  106,  190,  247 
Posing  the  sitter,  197 
Position  of  background,  206 
in  landscape  work,  240 
Positive  bath,  44,  273 
Positive  paper,  new  method  of  pre¬ 
paring  a  paper  that  will  keep, 
277,431 

paper,  washed,  275 
printing,  269,  280 
Positives,  alabastrine,  189 
Pouncy’s  carbon  process,  402 
Pouring,  424 

Preservatives  for  dry  plates— 
clove,  373 
cochineal,  370 
coffee,  371 
gum  gallic,  374 
morphia,  374 
pyrogallic,  369 
resin,  373 

tannin,  371  * 

tea,  371 


*  • 


488 


INDEX. 


Pressure  frame,  283 
Printing,  280,  284 
Printing  bath,  273 

new,  for  permanent  paper, 

277,  431 

Printing  in  the  camera,  384 
Printing  in  clouds,  184 
Printing,  failures  in,  336 
frames,  45,  283 

on  glass  by  development,  383. 
silver,  269 

Prints,  combination,  182 
finishing  the,  298 
mounting  of,  299 
rolling  the,  300 
silver,  permanence  of,  300 
tested  if  well  washed,  297 
Projection,  panoramic,  108 
plane,  106 

Pyrogallic  preservative  for  dry 
plates,  369 
Pyroxyline,  126 
alcoholic,  130 
influence  of,  130 
treatment  with  alkali,  132 
variable  character  of,  168 

R. 

Rapid  rectilinear  lens,  9,  81 
Red  lining  to  camera,  220 
Redevelopment,  32 
local,  169 

Reducing  over-developed  nega¬ 
tives,  176 
Reflectors,  124 
Reflection,  52 
Refraction,  52 

Relievo  process,  Woodbury’s,  396 
Rembrandt  effects,  194 
Remedies  for  poisoning,  418 
Repeating  back,  191 
Repetition  in  composition,  243 
Residues,  treatment  of,  379,432 
Resin  process,  373 
Retouching  the  negative,  178 
Retouching,  use  of  resin  in,  379 
Revarnishing,  how  to  do,  41 
Reversed  negatives,  400 
Ridge  roof,  115 

inclination  of,  117 


Rolling  prints,  300 
Ross’s  doublet  lens,  87 
Rotating  background,  206 
Rubber  varnish,  352 
Rules,  general,  47 

S. 

Salomon’s  glass  room,  120 
Sarony’s  glass  room,  119 
Scarlet  negatives,  173 
Schlippe’s  salt,  173 
Seasons,  influence  on  landscape 
work,  227 

Sensitizing  paper,  44,  273 

new  method,  277, 431 
Serum  of  milk,  264 
Shade  printing,  280 
Shadows,  216 
Sharpness,  want  of,  317 
Shepard,  Dr.,  toning  formula,  291 
Silver,  bromide  of,  410 
chloride  of,  406 
iodide  of,  406 
prints,  permanence  cf,  300 
pure,  value  of,  157 
Sizing  the  film,  177 
Skies,  management  of,  210,  219,  230 
Sky  shade,  219 
Slides,  221 
Sliding  front,  29 
Slipping  of  film,  317 
Smeariness  of  film,  320 
Snow  landscapes,  215 
Softness,  231 

how  obtained,  165 
Solar  cameras,  266 
Sore  hands,  to  heal,  37 
Specks  in  the  film,  160 
Spherical  aberration,  58 
Splitting  of  film,  316 
Spots,  hazy,  323 
opaque,  324 
transparent,  321 
Stains,  14,  43,  327 
Stand,  15 

Steinheil  aplanatic,  10,  81 
Stereopticon  slides,  386 
Stereoscope,  256 
Storing  negatives,  186 
Stopping  out,  180 


INDEX. 


439 


Stops,  92,  211,  223 
Streaks  in  the  negative,  31,  320 
Sugar  in  development,  165 
Sulphide  of  potassium  for  intensi¬ 
fying,  172 
Sun  printing,  280 
Sunlight  in  glass  room,  122 
Surface  stains,  327 
Swan’s  carbon  process,  399 
Swing-back,  148,  223,  225 

use  in  landscape  work,  151 
portraiture,  130 
Swinging  bath,  158 
lens,  131 

Syrup  for  keeping  negatives  moist, 

347 


T. 

Tank,  washing,  295 
Tannin  process,  371 
Tea  process,  371 
Temperature  of  glass  room,  123 
Tents,  346 

Theoretical  considerations,  404 
Thinness  of  film,  310 
Tissue,  carbon,  399 
Toning,  232,  288 
bath,  46 

formulae,  289,  290,  291 
and  fixing  baths,  292 
Top-light,  excess  of,  201 
Transparencies,  386 
Triplet  lens,  83 
Tripod,  how  made,  221 
chemical,  423 
Tunnel  system,  124 
Two-bath  system,  155 


U. 

Uranium  intensifying,  174 
Unsatisfactory  results  in  portrait¬ 
ure,  200 

V. 

Varnish,  37 

effects  of  too  thin,  41,  432 


Varnish — 

India-rubber,  352 
negative,  375,  431 
Varnishing,  37,  38,431. 

failures  in,  40,  41,  330, 432 
Veiling,  302 

Velvet  drapery,  194,  197 
Ventilation,  28,  110,  121 
box,  111 
View  lens,  9,  78 
Vignetting  with  cotton,  286 
by  development,  287 
with  a  frame,  285 
glasses,  285 
with  a  lens,  287 
on  the  negative,  287 
with  paper,  286 
by  a  screen,  288 
Viscid  liquids,  to  filter,  429 


W. 

Washed  sensitive  paper,  275 
Washing  the  negative,  36,  169 
prints,  46, 295 
Washing  tank,  295 
Wax-paper  process,  264 
Weakening  of  negatives  in  fixing, 
330 

Weather,  indications  of,  229 
Weighing,  420 
Weights,  421 

Wenderoth’s  glass  room,  118 
Willis’s  aniline  process,  396 
Wind,  the,  226,  229 
Wood-cuts,  copying  of,  251 
Wood  surfaces,  to  blacken,  428 
Woodbury’s  relievo  process,  396 
Woodward,  Dr.,  microscopic  pho¬ 
tography,  259 
Woodward’s  camera,  266 


Xyloidine,  130 

Z. 

Zentmayer  lens,  86 


SUPPLEMENT  No.  2. 


1876. 


I.— PERMANENT  SENSITIZED  PAPER. 


During  the  last  three  years  I  have  devoted  much  attention  to  finding  a 
method  of  preparing  sensitive  paper  which  should  be  capable  of  being  kept  for 
a  long  period  of  time  without  losing  the  power  of  affording  good  prints.  I  have 
I  believe  completely  succeeded,  having  now  in  my  hands  paper  which  was  pre¬ 
pared  in  November,  1873  and  which  can  still  be  used  for  printing.  Other  speci¬ 
mens,  also  in  condition,  were  prepared  in  March,  1874.  In  the  course  of  this 
investigation  I  have  also  learned  that  very  much  depends  on  the  mode  of  keeping. 
Not  that  it  is  necessary  to  use  chloride  of  calcium  boxes,  or  any  troublesome 
method  of  preservation,  but  that  certain  causes  that  have  not  apparently  been 
hitherto  suspected,  aid  greatly  in  the  rapid  deterioration  of  silvered  paper. 


The  spontaneous  darkening  of  sensitized  paper  depends  upon  the  reduction  of 
the  silver  salts  contained  in  it.  Therefore  to  aid  in  its  keeping  it  seemed  desirable 
to  place  in  contact  with  the  silver  salt,  substances  capable  of  affording  either 
oxygen  or  chlorine.  One  substance  there  was  which  offered  both  these  elements. 
This  was  chlorate  of  potash,  a  substance  which  I  believe  has  been  suggested  for 
use  in  the  interval  since  I  commenced  experimenting  with  it  but  had  not  been 
before.  Neither  has  the  proper  method  of  using  it  to  the  best  advantage  been 
indicated.  Other  substances  have  proved  themselves  useful,  viz:  lactic  acid  and 
nitrate  of  uranium. 

The  different  formulas  from  which  satisfactory  results  were  obtained  were  as 
follows : 


[Formula  No.  1 .) 


Nitrate  of  silver, 
Chlorate  of  potash, 
Dilute  lactic  acid 
Water, 


40  grains. 
20  “ 

,1  drachm. 
1  ounce. 


The  “ dilute  lactic  acid”  is  that  which  is  met  with  in  commerce  under  that 
name  and  at  moderate  prices. 

This  formula  was  used  in  November,  1873  and  the  paper  then  prepared  was 
found  in  April,  1876  to  be  in  condition  for  use.  Though  not  perfectly  white,  its 
color  was  not  more  than  what  disappears  of  itself  in  the  fixing  bath.  I  feel  no 
doubt  that  had  this  paper  been  preserved  under  the  conditions  which  will 


2 


presently  be  described,  and  which  I  had  not  made  out  at  the  time  that  this  paper 
was  prepared,  it  would  at  the  end  of  30  months  have  been  quite  white  and  pure 


( Formula  No.  2.) 

Nitrate  of  silver,  - 
Chlorate  of  potash, 

Dilute  lactic  acid,  - 
Nitrate  of  uranium, 

Paper  after  this  formula  was  prepared  in  March  1874. 
after  preparation,  it  was  found  to  be  in  good  condition.  I  think  the  nitrate  of 
uranium  has  perhaps  some  tendency  to  aid  in  the  keeping  qualities.  It  is  how¬ 
ever  by  no  means  an  essential,  as  formula  No.  1  sufficiently  proves. 

It  seems  unnecessary  to  remark  that  both  this  paper  and  the  preceding  are 
intended  to  be  fumed  but  cannot  be  expected  to  keep  after  fuming. 


45  grains. 

20  “ 

1  drachm. 

16  grains. 

In  April,  1876,  25  months 


METHOD  OF  PRESERVATION. 

In  my  experiments  I  was  at  first  under  the  impression  that  in  a  tin  roller  or 
cylindrical  case  with  a  tightly  fitting  cap  sliding  several  inches  over  it,  there 
was  a  complete  exclusion  of  light.  Experience  showed  this  not  to  be  the 
case.  Sensitized  paper  placed  inside  of  such  a  case  and  additionally  protected 
by  wrapping,  kept  better  than  similar  paper  lying  loose  in  the  case.  This  fact 
has  proved  to  be  very  important,  and  a  disregard  of  it  may  prevent  the  keeping 
of  paper,  otherwise  capable  of  very  long  preservation. 

Another  remarkable  observation  was  the  following.  The  dark  yellow-brown 
paper  used  for  making  “buff”  envelopes  seemed  by  reason  of  its  color  par¬ 
ticularly  well  suited  for  covering  rolls  of  sensitive  paper.  It  proved  on  the 
contrary  to  have  a  distinctly  injurious  effect.  Thus  when  a  sheet  of  sensitive 
paper  was  rolled  up  around  itself,  and  then  covered  with  this  buff  envelope 
paper,  all  the  parts  of  the  sensitive  paper  in  contact  with  the  buff,  darkened 
much  more  rapidly  than  the  portions  which  had  a  thickness  of  the  sensitive 
paper  between  them  and  the  buff.  This  action  showed  itself  first  on  the  part 
in  contact  with  buff,  that  is  the  back  of  the  sensitive  paper  changed  first,  and 
gradually  this  action  penetrated  through  to  the  face. 

I  therefore  recommend  to  proceed  as  follows.  Take  a  wooden  roller  not  over 
an  inch  in  diameter,  and  dry  it  thoroughly.  Place  two  sheets  of  the  sensitive 
paper  face  to  face,  roll  them  tightly  around  the  roller,  and  continue  with  more 
sheets  until  a  stout  roll  is  made.  It  is  a  great  mistake  to  separate  the  sheets 
under  the  supposition  that  this  aids,  on  the  contrary,  they  help  to  make  each 
other  keep.  It  is  therefore  better  to  make  one  large  roll  than  many  small 
ones. 

After  finishing  the  rolling,  draw  the  roller  out,  and  stuff  the  open  space  with 
clean  dry  raw  cotton.  The  object  of  this  is  to  prevent  all  circulation  of  air, 
air  brings  with  it  dampness,7  which  is  unfavorable,  of  course.  But  besides 
dampness,  there  is  a  certain  quality  in  the  air  which  tends  to  deteriorate  the 
t  paper.  This  quality  is  expended  in  its  action  :  the  more  the  air  changes  the 

oftener  will  this  action  be  renewed. 


The  next  step  is  to  cover  the  roll  of  sensitized  paper  with  clean  paper.  But 
this  cover  must  not  only  be  clean,  but  pure,  paper,  and  therefore  the  best  way 
in  my  opinion,  is  to  use  plain  photographic  paper.  Thus  prepared  and  covered 
with  an  outer  roll  of  opaque  hardware  paper,  the  roll  may  be  laid  in  a  perfectly 
dark  and  tight  drawer. 

If  however  it  is  intended  to  make  the  paper  keep  as  long  as  possible,  it  will 
be  well  to  enclose  the  roll  in  a  sheet  of  paper  saturated  with  solution  of  rubber 
and  pasted  down,  and  rapidly  dried.  This  should  then  be  placed  in  a  tin 
roller,  and  the  roller  in  a  dark  closet. 

It  should  never  be  forgotten  that  paper  which  is  intended  to  be  kept  for 
some  time  will  need  to  be  sensitized  with  a  much  completer  exclusion  of  light 
than  ordinary  sensitized  paper.  The  slight  influence  of  weak  light  admitted 
during  sensitizing  will  be  entirely  without  effect  when  the  paper  is  immediately 
used.  But  if  the  paper  is  to  be  kept  for  some  time,  this  slight  impression  may 
be  the  means  of  completely  destroying  it.  I  therefore  advise  to  take  the  same 
care  as  in  preparing  paper  for  positive  development. 

The  method  of  using  nitrate  of  cobalt  given  to  the  first  supplement,  for 
obtaining  fine  sepia  tones,  cannot  be  combined  with  this.  Paper  containing 
nitrate  of  cobalt  will  not  keep  for  any  length  of  time,  even  by  addition  of 
chlorate  of  potash. 

I  entertain  no  doubt  that  paper  prepared  by  either  of  these  formulas,  and 
especially  the  first,  might  be  advantageously  manufactured  for  sale. 


II.— DRY  PLATE  WORK. 

CHLORIODO BROMIDE  EMULSION  PROCESS. 

In  the  first  supplement  to  this  Manual,  are  full  details  of  the  method  of  preparing 
and  Using  this  emulsion.  It  remains  here  to  describe  an  additional  improvement 
made  to  the  process. 

It  is  a  well  known  fact  that  wet  plates  will  under  trying  circumstances, 
suffer  from  blurring.  Landscapes  in  which  very  dark  objects  are  thrown  against 
verjr  light  ones,  or  interiors  with  brightly  lighted  windows,  are  exposed  to  this 
defect.  Emulsion  plates  made  with  the  chlorobromide  process  are  much  more 
exposed  to  this  defect,  and  from  much  slighter  causes  than  wet  ones  and 
therefore  an  application  to  the  back  of  the  plate  is  much  more  necessary  than 
with  wet  plates. 

By  the  introduction  of  an  iodide  into  the  emulsions,  as  I  have  already  described 
in  the  first  supplement,  I  have  succeeded  in  bringing  the  emulsion  plates  to 
approximately  the  same  level  as  the  wet.  But  even  Avet  plates  when  used  for 
landscapes  and  interiors,  are  the  better  for  protection  from  behind,  and  I  have 
during  the  winter  of  1875-76  devoted  a  great  deal  of  time  to  studying  the  best 
means  of  obtaining  absolute  protection  from  blurring.  I  believe  that  I  may 
claim  to  thave  been  the  first,  now  many  years  since,  to  propose  the  method  of 
coloring  the  film  to  accomplish  this  result.  The  difficulty  lies  in  this,  that  most 
coloring  matters  applied  to  the  film,  distinctly  diminish  the  sensitiveness. 


4 


I  have  lately  compared  all  the  coloring  matters  that  have  been  suggested  for 
use,  and  also  very  many  others,  and  find  scarlet  coralline  to  be  the  best.* 
Coralline  has  been  before  tried,  but  always  with  a  diminution  of  sensitiveness. 
In  fact,  it  has  been  generally  understood  that  all  coloring  of  the  film  entailed 
a  loss  of  sensitiveness,  and  I  notice  that  the  Liverpool  Dry  Plate  Company,  with 
commendable  frankness  state  in  their  advertisements  that  the  colored  plates, 
whilst  free  from  blurring,  are  less  sensitive.  I  have  been  so  fortunate  as  to  find 
the  method  of  using  coralline  which  avoids  this  difficulty  wholly.  A  plate 
covered  one-half  with  the  colored  film  and  the  other  half  with  the  uncolored, 
and ‘exposed  under  a  stereoscopic  negative  will  give  transparencies  of  exactly 
equal  strength.  The  most  careful  comparison  fails  to  detect  any  inferiority  of 
sensitiveness,  even  with  exposures  made  purposely  so  short  as  to  tax  the  powers 
of  the  film  to  the  uttermost. 

This  result  is  accomplished  also  in  the  simplest  manner.  It  is  only  necessary 
to  add  the  alcoholic  solution  of  coralline  to  the  finished  emulsion  and  employ  it 
precisely  as  usual.  Neither  is  there  any  necessity  for  special  means  of  removing 
the  color  from  the  plate;  this  I  should  consider  a  fatal  objection.  Coralline  has 
the  inestimable  advantage  that  it  disappears  of  itself  in  the  operations  of  devel¬ 
oping,  fixing  and  washing. 

The  best  scarlet  coralline  (the  yellow  coralline  sometimes  called  aurine  i9 
entirely  unsuitable)  is  to  be  dissolved  in  alcohol  48  grains  to  the  ounce.  The 
solution  takes  place  rather  slowly  and  several  days  should  be  allowed  with  occa¬ 
sional  shaking,  neither  is  it  ever  entirely  complete,  a  small  amount  of  dark  resi¬ 
due  always  remains,  even  after  standing  for  months.  To  each  ounce  of  finished 
emulsion,  from '6  to  10  minims  of  this  coralline  solution  is  to  be  added  and  well 
shaken.  The  emulsion  is  then  ready  for  immediate  use.  It  will  not  have  the 
strong  red  color  of  coralline,  but  a  buff  or  salmon  shade. 

I  cannot  leave  the  subject  of  emulsion  without  again  adverting  to  the  fact  that 
without  a  pyroxyline  of  the  right  character  it  is  a  mere  loss  of  time  to  attempt 
to  obtain  a  good  emulsion,  and  that  nine-tenths  of  the  failures  that  occur,  are 
attributable  to  this  cause. 


*In  this  connection  the  author  desires  strictly  to  limit  his  own  claims.  Having  been 
elsewhere  able  to  prove  that  the  idea  of  applying  color  to  the  film  originated  with  him,  he 
makes  no  claim  to  having  been  the  first  to  suggest  the  use  of  this  particular  color.  But  he 
believes  that  he  has  been  the  first  to  find  a  method  by  which  it  may  be  employed  without  a 
loss  of  sensitiveness. 


